Manta EFI problem

[Gordy]

75 Manta with efi. Starts and runs for 1 second and then dies out.
40 Pounds fuel pressure at cold start injector.
Ignition etc good- ran a jumper from battery to + side of coil to make sure it wasn't the ignition switch
Al sensors are new as is the mass air flow sensor.
checked all connections
tried a different ecu unit

Still starts right up and runs for a second and then just dies out. Stepping on gas pedal makes no difference.

I am still going to check the green wire to the coil to the ecu for continuity.
Other than that I'm stumped.

It seems like it is not getting fuel once the initial start up is complete. Plugs are dry and not wet with gas.
I made sure the air flap in the mass air sensor was not stuck.
Any ideas (other than putting a Weber on it)

[First opel 1981]

Originally Posted by Gordy 75 Manta with efi. Starts and runs for 1 second and then dies out. 40 Pounds fuel pressure at cold start injector. Ignition etc good- ran a jumper from battery to + side of coil to make sure it wasn't the ignition switch Al sensors are new as is the mass air flow sensor. checked all connections tried a different ecu unit Still starts right up and runs for a second and then just dies out. Stepping on gas pedal makes no difference. I am still going to check the green wire to the coil to the ecu for continuity. Other than that I'm stumped. It seems like it is not getting fuel once the initial start up is complete. Plugs are dry and not wet with gas. I made sure the air flap in the mass air sensor was not stuck. Any ideas (other than putting a Weber on it)

Use a voltmeter and make sure that the fuel pump is getting 12V when the ignition is on. Just guessing but it would seem that the fuel pump is connected to the wrong spot of the ignition.

[michaedo]

Worked on a Toyota that was doing the same thing. Ended up
being the run relay. Don't know why but there's a relay that
powers the fuel pump on start up and switches over to another
relay once the engine starts. Looking at an Opel diagram it does,
indeed, have a dual relay setup. Looks like there's a fuse involved
just before it. All this is on a page in a book, I'll be darned if I'd
know where to find them on the car. My bet is your (more than
30 year old) relay has bit the dust. Just guessin'.

[michaedo]

Originally Posted by First opel 1981 Use a voltmeter and make sure that the fuel pump is getting 12V when the ignition is on. Just guessing but it would seem that the fuel pump is connected to the wrong spot of the ignition.

Yeah, that's the way I found it. I checked voltage at the pump.
Got 12v at startup only to lose it once the engine started running.

[First opel 1981]

Originally Posted by michaedo Worked on a Toyota that was doing the same thing. Ended up being the run relay. Don't know why but there's a relay that powers the fuel pump on start up and switches over to another relay once the engine starts. Looking at an Opel diagram it does, indeed, have a dual relay setup. Looks like there's a fuse involved just before it. All this is on a page in a book, I'll be darned if I'd know where to find them on the car. My bet is your (more than 30 year old) relay has bit the dust. Just guessin'.

An interesting anecdote.
The 1974 Vega had a weird setup that when you started the car the electric fuel pump would work but then it went through the oil pressure sending unit. If the engine lost oil pressure, the fuel pump would cut out leaving you stranded.
I made quite a few dollars replacing (or wiring past) oil pressure sending units in Vegas, whick also led me to find an Opel GT out in the middle of nowhere. (their Vega had the problem and the person just happened to have a GT that was broke down)

[wrench459]

John drilled this into me.
Check the ground strap from engine to chassis. The negative voltage drop should be under .5 volts.
Next would be to check ignition and fuel systems. I'm lazy so I'll insert a gas sniffer probe and look for >1000 ppm's HC. If over 800 or more we can probably say that the injectors,ecm,fuel pump are working.

[davegt27]

Take a light tester and go to the starter solenoid

On a 75 there are two prongs sometimes these get mixed up when they are reconnected

One will give voltage on start and one will give voltage all the time when key is place in the run

(Don’t forget the old run/start thing. that is in the Chevy world if a car starts and runs and you release the key and shuts off then the start/run wires are hooked up backwards)

Back to Opel EFI

Pwr for the EFI system comes from the starter relay (the starter solenoid has two prongs)

pwr from one prong of the starter solinoid should come on and stay on after the car starts (light tester can be a big help)

If it passes that test you move on to the dual relay
It’s been years and years since I played around with one
But this might help (pg 21)

http://www.texas912.org/912E%20T...l%20Manual.pdf

before i found out you could go down to a bug shop and buy a dual relay i would have to take my dual relay apart and jumper some wires out to get the car to run



*note--AFM (air flow meter AKA flapper meter) -- MAF (Mass Air Flow AKA Hot wire) the Opel does not have a MAF meter

The AFM has a switch in it to control the fuel pump but this functions after the car comes off the start circuit

Or in other words the fuel pump will run one way on the start circuit and through the AFM switch on the run circuit

It is assumed once the car is running and on the run circuit air going through the AFM and will keep the fuel pump activated

Hope that makes sense but the wire diagram on pg 21 shows how it works sort of

If the car wrecks and no air flow is going through the AFM and even if the key is still on the fuel pump is shut off

So in other words it’s a safety device

Those are the first initial check I would make
After that you your back to the basic L-Jetronic troubleshooting

The dual relay does fail a lot

I can go on to the other stuff if you want


HTH
Davegt27

[Gordy]

Thank you for all the tips. I will start by checking the engine ground, the wire from coil to ecu, and I do have another dual relay setup I can switch out. Thanks,

[opelnut10]

Originally Posted by Gordy Thank you for all the tips. I will start by checking the engine ground, the wire from coil to ecu, and I do have another dual relay setup I can switch out. Thanks,

Before you change out the dual relay, find the fuel pump wire in the trunk area,(under the mat on the driver's side) unplug the connecter and plug the pump side onto the side marker, turn on the parking lights and the pump should run start the engine and see if it continues to run, if so it is the duel relay. Also check the ECM in the kick panel and make sure moisture is not running down the antenna wire and dripping onto the ECM. If this is happening take the antenna loose at the fender and seal it with RTV, take out the ECM and dry it with a hair dryer or heat gun at low temp.

[tekenaar]

OK, power for the fuel pump is supplied by one of the relays in that "dual relay" (located next to the injector resistor pack, typically) during the engine start and by a set of contacts in the air meter once engine has fired and there is continuous air flow through the air meter. Your indications are that there's nothing wrong with your "dual relay" but that the problem may be with the air flow meter contacts instead.

A quick test is to remove the air filter lid with the air meter and push the air meter vane/flap gently with a screw driver while the ignition key is "ON" . . . the fuel pump should run as soon as the flap is moved slightly off the "rest" position.

Here's detailed Bosch L-jetronic FI HTML

[Aardvaark]

Originally Posted by tekenaar OK, power for the fuel pump is supplied by one of the relays in that "dual relay" (located next to the injector resistor pack, typically) during the engine start and by a set of contacts in the air meter once engine has fired and there is continuous air flow through the air meter. Your indications are that there's nothing wrong with your "dual relay" but that the problem may be with the air flow meter contacts instead. A quick test is to remove the air filter lid with the air meter and push the air meter vane/flap gently with a screw driver while the ignition key is "ON" . . . the fuel pump should run as soon as the flap is moved slightly off the "rest" position.

If it is the flow meter pump run contact set, you can cut the silicon seal and remove the plastic cover lid on the meter to access the contact points to carefully clean them. Be careful. Then reseal the lid with silicon.

[Gordy]

I have had nothing but trouble with the EFI unit since I put it on the car. Yanked it off and put a 32/36 Weber on it and left the sprint exhaust manifold on it. Took the high pressure fuel pump off and replaced with a low pressure unit. Just need to wire in the fuel pump and will be set to go. Ran stronger when I had the Weber on before than it did even when the efi wasn't acting up.
If there is an efi expert that wants to make a few bucks I wouldn't mind sending the whole unit to him to check it all out and see where the problems might lie.

[Aardvaark]

Originally Posted by Gordy I have had nothing but trouble with the EFI unit since I put it on the car. Yanked it off and put a 32/36 Weber on it and left the sprint exhaust manifold on it. Took the high pressure fuel pump off and replaced with a low pressure unit. Just need to wire in the fuel pump and will be set to go. Ran stronger when I had the Weber on before than it did even when the efi wasn't acting up. If there is an efi expert that wants to make a few bucks I wouldn't mind sending the whole unit to him to check it all out and see where the problems might lie.

Gordy.
I would be happy to check out your components on my '75 with a completely good EFI system to locate the problem. I'm not a Bosch L-Jetronic trained technician, but have been all through the system during my racing days and have the tools, digital multimeter, books and enough knowledge to find your trouble I believe. And there would be no charge since I'm retired and have time on my hands to do it component by component for entertainment.
If you're not in a hurry, I could return it to you at Springfield in September if you will be there. Or ship it back before if your in a hurry.
If someone else with more experience offers also, I would completely understand.
PM me if your interested in my offer.

[tekenaar]

. . . for '75 (and later) FI to my post #10 here for reference . . .

[Aardvaark]

Originally Posted by tekenaar . . . for '75 (and later) FI to my post #10 here for reference . . .

Good reference material!

Btw. Guess I'll fess up to a handful of mods I make to the injection on my '75's since we don't have emissions inspections in my area and they are easily undone.

To restore engine braking under deceleration, I render the deceleration valve
inoperative by either plugging the air passage in the hoses or plugging the vacuum line to it.

To improve throttle response, plug the dizzy vacuum retard and set the idle advance to 6-7 deg btdc. For about 31-32 total advance.

To also improve throttle response, I render the EGR inoperative by plugging the steel line into the EGR valve. I don't just plug the vacuum line because I believe the EGR valve tends to leak after awhile.

I've also played around with pinching off the fuel return line from the fuel regulator to boost injector line pressure, but never saw any improvement.

Also, I messed around with the air flow meter potentiometer initial
spring tension settings to see if a slightly richer or leaner fuel curve would help, but could never see any improvement using my butt Dino and stop watch or lap times.

With a proper wheel dyno, it's possible slight changes could be seen. Dunno.
Maybe somebody has played with this?

Now I can sleep well at night.

[Bill Hoffmann]

Originally Posted by Gordy 75 Manta with efi. Starts and runs for 1 second and then dies out.

There is a 10 gauge red colored wire that runs from the dual relay directly to the battery through a spade lug connector. If it is unplugged the engine will exhibit the symptoms you describe exactly.

Bill

[wrench459]

Originally Posted by Aardvaark Good reference material! To also improve throttle response, I render the EGR inoperative by plugging the steel line into the EGR valve. I don't just plug the vacuum line because I believe the EGR valve tends to leak after awhile. I've also played around with pinching off the fuel return line from the fuel regulator to boost injector line pressure, but never saw any improvement. Also, I messed around with the air flow meter potentiometer initial spring tension settings to see if a slightly richer or leaner fuel curve would help, but could never see any improvement using my butt Dino and stop watch or lap times.

My thoughts are to use the egr to our advantage. Go figure.
As for clocking the air flow meter its a hit or miss
It's fat as hell at idle or lean on the top end.
Why are we even messing the sorry fuel management of the '75?

[Aardvaark]

Originally Posted by wrench459 My thoughts are to use the egr to our advantage. Go figure. As for clocking the air flow meter its a hit or miss It's fat as hell at idle or lean on the top end. Why are we even messing the sorry fuel management of the '75?

These days my only goal is to make the idle and light throttle operation
smoother and throttle response at low speeds as seamless as I can. And to restore engine braking while coasting, particularly nice to have with the automatic trans. When the A/C compressor kicks in and the headlights are on, the rpm dropped more then was good for a smooth strong idle when the idle was set by the fsm. I've acquired a handful of new carburetor idle stop anti-diesel solenoids and may use one to make an rpm kick up for when the a/c clutch engages.

Back in my SCCA showroom stock racing days, the goal was to find any advantage and still pass post race inspection, even a 1 hp gain was big with those cars. So messing with the fuel curve with the flow meter was played with. But like I said, none of us Opel racers I conferred with could find a better setting. We weren't as sophisticated as today with rolling dyno's and test equipment and went by our seat-of-the-pants stop watch times and lap times.

The guys with cars that used K-jetronic like Rabbits and Saab 99's
would play with their injection too, but never really found an advantage.
I found this out later when I switched to a '78 Rabbit and began asking my buddies. What really helped those stock cars was a fresh valve job every few races and for the big budget guys, a professional blueprinting to the FSM so the engine was in top form. Since engines could be torn down on the top finishers and by protest, care had to be taken not to do a trick valve angle cut, any port or head polishing at all or shaving the head thinner than allowed by the FSM. The bottom line is that the top cars had fresh engines and fresh shaved tires for qualifying and the race.

[davegt27]

Originally Posted by wrench459 My thoughts are to use the egr to our advantage. Go figure. As for clocking the air flow meter its a hit or miss It's fat as hell at idle or lean on the top end. Why are we even messing the sorry fuel management of the '75?

Learning the early 75 FI gives you a real good base for understanding all FI

After installing FI on my 75 GT I tried all kinds of stuff. I backed things up buy going to the drag strip every weekend

Some of the things I tried

2nd design fuel injectors (often the cause of a lot of problems is bad injectors)

1.5 Head (the plugs where nice and tan with the 32/36 but when I went to FI they where black)

Took the electronics card out of a 1.9 AFM and installed it in a 240Z AFM

Tried a 2.0 Renault AFM

75 sprint header

Pacesetter header

3.67 gears

Ran around with a friends Haltech AFR meter (I think it was to sensitive to help out much)

Switched to a 2.0 FI setup (the AFM is the same size as the 240Z AFM)

Later I took that basic understanding and I was able to get my L-Jet 85 MR2 to pass smog with a burnt out CAT

Using an AFR meter to tune with

Basically I was able to tune around the AFM by using the AC idle UP bypass

It has a larger air line with a little knob on it, this turned out to be a neat little tuning device

I could adj the reading on the AFR meter by adding or taking away air
So I did three things, adj spring tension on the AFM flapper, adj the idle screw on the AFM and I would bypass air around the AFM with the AC idle up solenoid

Took hours but was kind of fun

Davegt27

[wrench459]

Good post Dave.
That one would be great to print out and save for future reference.
While where mixing and matching FI systems another spot that might come in handy is the BCDD(boost controlled deceleration device) valve.
NO dont even think it. That boost valve is not what you think it is.

[Gordy]

Bill, I will check that red wire as I had the car at a trans shop for trans fluid/filter change when the problem developed. Who knows what they may have knocked loose while messing with the car.

[davegt27]

Originally Posted by wrench459 Good post Dave. That one would be great to print out and save for future reference. While where mixing and matching FI systems another spot that might come in handy is the BCDD(boost controlled deceleration device) valve. NO dont even think it. That boost valve is not what you think it is.

one thing i did not try was to add a 2nd cold start injector

it turns out the place where the EGR tube attachment point is almost the same size as the bolt pattern for the cold start injector

so i opened up the hole a little and installed a cold start injector (it works off 12V)

so the next step would be to add a pressure switch the developed continuity at 0 manifold vacuum

had it all wired up but i was to poor at the time to buy a good CSI (cold start injector)

all the ones i got from the junk yard where bad.

for racing like Aardvaark was doing i would mode the system to have the TPS go full throttle enrichment before it got to full throttle

the FI system goes to full enrichment at WOT

Davegt27

[Aardvaark]

Originally Posted by davegt27 for racing like Aardvaark was doing i would mode the system to have the TPS go full throttle enrichment before it got to full throttle the FI system goes to full enrichment at WOT Davegt27

Actually I did try that, but not by modding the TPS. Instead I made a jumper with a toggle switch around the max enrichment position of the TPS and could
trigger max enrichment from the drivers seat to see what would happen at various speeds. This was off the track during testing on a favorite stretch of country road which the Iowa DOT had conveniently marked out 1/8 and 1/4 miles with aircraft enforcement paint strips.
My conclusion was that the stock AFM was really pretty close to the mark, and extra gas didn't help any any speed. The final conclusion was the the stock AFM which the rules stuck us with was just too undersized to flow enough air and couldn't come up with anything that would allow more air around the AFM and stay within the rules for inspection. If more air could have been found, then triggering max enrichment may have helped.

At one point I even built a small potentiometer in a Radio shack case to
adjust the AFM voltage while underway to see what would happen but that ended in a very poorly running Opel and was ditched pretty quick.

Dave. I like your work with moving the stock AFM circuit board to a larger AFM for how I use the car nowadays. Did you have any luck with the 240Z or other lager then stock flapper style flow meters? I'm sorry to say I'm not quite following your second to last post of what you have tried regarding bigger folw meters. Did any of them prove to help?
Thanks.

[davegt27]

Dave. I like your work with moving the stock AFM circuit board to a larger AFM for how I use the car nowadays. Did you have any luck with the 240Z or other lager then stock flapper style flow meters? I'm sorry to say I'm not quite following your second to last post of what you have tried regarding bigger flow meters. Did any of them prove to help?

Nope it did not work

In the pits I installed the modified AFM and adj the spring tension until I had a nice smooth idle and crisp throttle response

Made a pass in the 1/4 and the car would not rev past 5300 RPM
Went back and loosened the spring and made adjustments until I had black smoke coming out the tail pass
Made another pass and same thing it would not rev pass 5300 RPM

Went back and took it off
My 1/4 mile times showed no improvement
The fact that my plugs where already black should have told me it would not make any difference
I needed more air

The only time I could get it to lean out was when I took the intake manifold off took it to a car wash and cleaned out all the gunk

After I put the manifold back on and ran the car the exhaust manifold glowed
Which meant I had leaned the car out (no other changes where made)

I was a real beginner back in those days
Having an Adj fuel pres regulator and an AFR meter is essential to make any adj to the FI system

Another way to get more air would have been to use the Aux Air valve to bypass air around the TB
But the AFM would still be a problem

Later I went to a 2.0 FI system and even then the 1/4 mile times did not change (I did have a slight loss of low end torque)

Anyway there you have it
Davegt27

[Aardvaark]

Originally Posted by davegt27 Anyway there you have it Davegt27

Thanks Dave. At least it's nice to know me and the other racers weren't missing something.

Also, Gordy PM'ed me to say that Bill Hoffman was correct and that the red wire got knocked loose and was the cause of the FI problem of initially firing but not continuing to run. So our PM'ing plans to test out his components won't be required. So now my plans to nap afternoons is back on.