71 GT Electric Fuel Pump

[poffenroth]

Hi folks, I think I have this right - can someone verify for me?

I want to upgrade to an electric fuel pump. My mechanical fuel pump is starving the engine for fuel when the engine gets up to normal operating temperatures, and it is leaking oil anyway. I've already routed the fuel lines away from the being over the head, so I don't believe it is a vapour lock scenario. The motor is the stock 1.9 with a weber 32/36 DGAV and Pertronix ignition. On re-routing the fuel lines, I moved the fuel filter up by the carb. I can watch it go dry as the engine gets warm. Neat!!

I'm going to track down a low pressure high volume fuel pump (probably the Carter than has been mentioned before), and a fuel cut-off switch (oil pressure). However, I have 1 question - with the low pressure high volume pumps, is it still necessary to plumb in a fuel return line from the pressurized side of the fuel pump, or does it work like the standard mechanical fuel pump without the return line?

Thx!

[markandson]

No return line necessary, the pump is internally relieved. I have one that is not installed yet, I just verified this on the installation sheet.

[GTJIM]

You may need a fuel pressure regulator to get the pressure down to 2 1/2 to 3 PSI that the Weber requires but a return line is not necessary unless you still have vapour lock problems. Then the returning fuel will keep things a bit cooler in the fuel line. The electric pump should hold the pressure against the regulator without any trouble and not need a return line. Just follow the instructions that come with the pump you use though!

[opelbits]

Just like stock.

I tried one of the Facet type pumps (square block) and didn't like it. Made too much noise. So, I switched to a rotary vane type (round cylinder), much better. I installed it back by the axle along with a metal fuel filter between it and the tank. When I had the Facet, I made a plate which I mounted to the car using the unused rear swaybar bolt holes.

This past weekend I moved my fuel line to go in front of the radiator and come thru the air cleaner snorkel hole. I had a plastic see-thru filter right before the carb, but removed it for the same reason you will, watching it go dry as the vapor-lock conditon began.
My symptoms before: starts fine, runs fine. Get it all hot after a drive and the idle becomes rough and it wants to stall. Sitting still after getting good and hot and it does it, too. Now, after a good run on the highway it idles just fine. Sit too long and will start to run rough and want to die.
This could be for one of two reasons, one, I'm running a K&N filter on top of the carb, this sucks in hot air when the car is not moving. It has been suggested that the stock air cleaner snorkel always draws in cooler air from the front and helps keep the carb cool.
Or, two, when sitting still, the radiator fan pulls air thru the radiator which means air has to come from somewhere to the front of the radiator and if the unused air cleaner snorkel hole is left uncovered, it may be drawing the already hot air from the engine side thru the hole to the front. I suspect this because my temp gauge will start to go up. If it was just the carb getting hot and causing the fuel to boil, it should mean that the mixture is getting too lean and combustion temps are going up, accompanied by maybe some spark knock/ping/detonation once I get moving.
But I think it may be both.

[namba209 (R.I.P.)]

Opelbits, I think the overheating at idle are two fold and both have to do with engine speed. The first is the fan is not going fast enuff to move the air sufficiently across the radiator for a good heat exchange and second the waterpump is doing the same thing, not moving enuff coolant through the engine. When it gets into an overheat situation, try runing the engine about 1200 RPM and watch the temp gage. You should see the gage go back to normal rather quickly. HTH.

[poffenroth]

Well, a quick visit to my local Opel Parts Supply (KWILFORD, who happens to live about 5km from me) and he has a spare mechanical pump.

So... I started to take my old one off, and it is FULL of crap in the fuel screen.

So... see my other thread about a dirty gas tank for pictures...

I still plan on the electric fuel pump upgrade, but am going to wait for a bit until I get the tank clean and the alternator upgraded.

Markandson - Thanks for the info!

[snerre]

I installed the electrical pump this weekend. Worked very good. I used a relay and control current from ignition.

But you shuld check up the pump. Two types are at the marked. One with more pressure than the other, this is ment to be placed back whit the gas tank.

If you need to have the pump in the engine room, you must buy the pump whit low pressure.


best reguards


Martin

[opelbits]

Opelbits, I think the overheating at idle are two fold and both have to do with engine speed. The first is the fan is not going fast enuff to move the air sufficiently across the radiator for a good heat exchange and second the waterpump is doing the same thing, not moving enuff coolant through the engine. When it gets into an overheat situation, try runing the engine about 1200 RPM and watch the temp gage. You should see the gage go back to normal rather quickly. HTH.

I have an 800 rpm idle, which should be plenty for maintaining a stable temperature. I mean, Opel did it and my engine is not very far from stock: Euro 2.0, 32/36 DGAV, Pertronix in a '74 distributor, slightly modified intake manifold, stock GT exhaust, and the heavy duty radiator from OGTS.

Seems to me a 1200rpm idle would be a bit extreme.

[baz]

hi opelbits ,
a few things to think about
if the fuel filter in front of the carb was going "dry" as you watch it then its more likely to be a fuel flow problem (pump or line blocked or vent blocked ) (see dirty tank thread ) for that problem
first try to get it to do it with the gas cap off (no vapour lock in tank )
if it will not then look to tank vents
if it will try to take gas cap off then the fuel pipe off before the pump and blow it back to the tank(do with little to no gas in ) this will clear any blockage for a short while to see if its dirt , if it blows back with no resistance then plug the pipe and put a short bit of pipe on the pump so you can blow through to the carb , if this blows through ok then scratch head and look puzzled as we all do
this would make me think the pump is not working right


you dont say but to get running problems you describe i would think the temp must be going up when you are at idle and if so i would think its time to see if the water pump is ok (they do rust and loose blade efficiency after years of service ) or the thermostat might be stuck and need changing both of which would run ok at speed but give hot symptoms at slow street /idle speeds

[namba209 (R.I.P.)]

Opelbits, my suggestion was to run the engine at 1200 RPM for a short time watching the temp gage. If the temp does go down, then one of the two things I mention earlier, or both is the problem. Basically, this is a trouble shooting technique.

[opelbits]

namba-
I slightly misunderstood, sorry. When it has that problem and I rev it up or start driving again, the temp goes down. It does not seem to do it if I start the car and just let it idle, as far as I recall it is only after it gets nice and hot from a drive and then let it idle for 5 or 10 minutes.

The waterpump has been replaced as has the thermostat. A couple of years and a couple thousand miles on each. But who knows, sometimes things do not last as long as they should.

Baz-
The tank was cleaned and relined and the vent hoses replaced when the motor went in, about 8k ago. The pump is less than a year old and has less than 2k on it.

[namba209 (R.I.P.)]

O.K. no problem, let's try one more idea from my USAF days. After a drive when the engine is up to normal operating range, let it idle for about 15 minutes. Here's the reasoning, and you can apply the theory to engines as well, after an aircraft makes its final application of brakes, after landing, they will not start cooling down until after 15 minutes. That's the most dangerous 15 minutes around an aircraft. It takes that long for the heat to dissipate with no cooling air flow around them. So after you drop the engine RPM down from a high setting, it may take that long for the built up heat to dissipate, and because the water pump and fan are at idle speeds, they aren't as efficient. Give it a try and see what happens.

[opelbits]

Ah, yes, the dreaded 'heat soak'...


I'm working on a cold air setup for the carb, right now. I found a Benz in the junkyard a few years back with a 32/36 and TWM plenum. I'm looking for the right air filter to put in front of the radiator support to put this all together. Might even wrap it with some sort of insulation.

[tekenaar]

Here's my recommendation for low pressure fuel pump:



and safety device:

[tekenaar]

The OP6610 EFP safety switch is an SPDT (single pole, double throw) switch electrically with NC (normally closed), CO (common, switching) and NO (normally open) contacts. It is wired as follows: CO is wired to + side of fuel pump; NC is wired to "Start" position of ignition switch (only on during starting of engine); NO is wired to any switched 12V source (on when ignition key is in "On" position.

Operation is as follows: Ignition key in "On" position with engine off (no oil pressure), EFP does not run. Ignition key in "Start" position for engine start, pump runs from power from the NC contact to the CO contact until there is sufficient oil pressure to switch CO contact to NO contact, powered by switched 12V.

Pretty simple, no?

[spdkilz02]

is that adaptor something that napa, advanced auto, or autozone would have?

[baronbors]

I had the same problems with my GT- engine got hot after running awhile and didn"t want to re-start. A Pertronix and electric fuel pump solved every thing. I stuck my new carter up front temporarily along with a MG inertia switch but it works so well that I think it will stay for awhile

[spdkilz02]

i guess im still kinda confused about how to wire the thing with the OP switch...ill just have to search more then i already have...

[jeff denton]

Otto's way is as simple as it could possibly be. Mine uses a relay, a normally closed oil pressure switch (which also turns on an idiot light) and a momentary contact "priming switch" for bypassing the whole safety system momentarily. Quite a bit more complicated unless you are an electrician of sorts.
Make sure you understand the terms, SPDT means a switch that can connect the common terminal with two others, but not at the same time. NO means the switch is not connecting the terminals unless something tells it to. NC means the switch is connecting the terminals unless something tells it not to.
In this case it is oil pressure telling the switch what to do, no oil pressure (engine not turning) tells the switch to open the circuit to the fuel pump. But, when the starter is engaged the start command current flows through the switch's closed circuit to the fuel pump. The engine cranks, fuel flows, then oil pressure builds and closes the switch's circuit to give ignition voltage to the fuel pump instead of start command voltage, thus when the engine fires and you let off the start button (key) ignition voltage keeps the fuel pump going. If the engine quits turning for any reason such as a head on crash, rollover, bad clutch pedal dexterity (hopefully usually the latter) the fuel pump shuts off.
Hope this helps, I made it as simple as possible, I think! My scanner is on the blink, otherwise I'd draw a schematic for you. And I am NOT a computer troubleshooter...

[2 Fast 4 U]

I have a simelair kind of safety on my LPG installation only it works with a pick-up sensor, a single wire roled around the cable that comes from the coil and goes to the distributor. this gives a relais a signal to close a contact, and keep it closed when the engine is running.
when the coil stops giving pulses to the distributor the relais opens the contact a few seconds later.
and also if you turn the key to start the engine the relais is signaled to close the contact and if you don't start the engine the relais opens the contact a few seconds later.