Opel GT Forum banner

21 - 29 of 29 Posts

·
Registered
Joined
·
715 Posts
Gas, fuel, compression. Try Jeff’s suggestion. Sounds like the fuel delivery from your description. If spark & compression check out (Compression is probably fine if you had it running already).

Gas:
I’d start at the inlet to the fuel pump if gas should dump out at a pretty good rate. Install a tee and check the fuel pressure between the fuel pump & carburetor for close to 3 psig. If it’s the stock mechanical pump and it’s old my money is on that. The gas tank plugging up indicated by weak flow of gas before the pump.

Spark:
I usually check spark by removing all of the plug wires off the plugs keeping them away from any metal (ground) securing a spark plug wire around an 1/8” away from the side cam cover bolt and crank the engine (don’t hold it) I usually find a safe way to sandwich it underneath a little block of wood or something, you should see a nice blue spark.
Lastly the carburetor, most inspections can be done without removing it.
 

·
RunOpel
Joined
·
1,204 Posts
Jon I realize I never answered your question about the use of Goof off having any effects on the original paint. I use a plastic scraper along with applying the Goof off with a rag and vigorously rubbing, then use the plastic scraper. The over spray chips off leaving the original paint untouched. Have you had any success?
I would agree with Jeff, sounds like a fuel issue. Have you ever replaced the fuel pump? By the way, what did you pay for that 1970 Opel GT?
 

·
Registered
Joined
·
48 Posts
Discussion Starter #23
Jon I realize I never answered your question about the use of Goof off having any effects on the original paint. I use a plastic scraper along with applying the Goof off with a rag and vigorously rubbing, then use the plastic scraper. The over spray chips off leaving the original paint untouched. Have you had any success?
I would agree with Jeff, sounds like a fuel issue. Have you ever replaced the fuel pump? By the way, what did you pay for that 1970 Opel GT?
The Krud Kutter worked well initially, but there were some spots that wouldn't come off without a bit of scraping, and the scraping took off some of the original paint. I'll try Goof Off at some point, but for now paint is taking a backseat to getting it running better. I picked it up for $2200.
 

·
Registered
Joined
·
48 Posts
Discussion Starter #24
I pulled the inlet to the fuel pump and gas comes out in a steady stream. I pulled the hose off the carb and it comes out pretty fast while cranking, so I think the pump is ok. I can get it to start and somewhat idle, but if I touch the throttle it dies pretty much instantly. It actually ran the best when I had the fuel line disconnected at the carb, I don't know if this is just coincidence or not.

Does anyone know where to find a good description of how the choke operates/latches? I'm not sure if it's working how it should. It doesn't seem to be closing, so I may just need to re-adjust it.

Not helpful that it's over 100 degrees out now and I don't have AC in the garage.
 

·
Registered
Joined
·
715 Posts
I have the choke plates removed from mine. Especially with the hot weather you’re describing it shouldn’t be that critical. Vacuum leaks are at the top of the troubleshooting list if you have good cranking compression and spark.

I do use the fast idle cam on the choke assembly to assist with cold starting but the cover plates aren’t needed. That said I live in a warmer climate.
Let’s put the choke assembly aside for a minute.
Have you tried using the other adjustment screws yet?


Do this before you chase a vacuum leak.

The choke:
The choke has 3 hex head screws located on the white plastic choke cover if electric, it may be metallic if you have a water choke. Loosen those screws a little and turn the cover, you should do this when the engine is cold you’ll see the choke plates rotate (rotate until they’re almost until they’re close) once you have found the right direction to turn it. Don’t worry, if it’s the water choke the only thing underneath the cover is the BI metal spring. The choke fast idle screw slot faces the front of the vehicle. You’ll want to be sure that it’s not affecting the idle speed after the engine is warm. It should be adjusted while the choke plates are almost all the way closed and the engine is cold.
 

·
RunOpel
Joined
·
1,204 Posts
I couldn't agree with you more, getting it running is first priority. Your number one priority is getting ti drive it and having some fun, then tinker with restoration and modification :)
 

·
Registered
Joined
·
48 Posts
Discussion Starter #28
Finally think I made some progress. I measured the compression for another data point and got between 145-155 in all cylinders. I think the issue may have been the float or the float valve sticking closed. I got some starter fluid and it started fine with that. On its own it would sometimes start and run ok, and sometimes start and die. I gave the carb a decent whack near the bowl, and after that it seems to be running ok. Still need to run it longer and try a test drive. If this was the issue, is there any way to prevent it happening again? I just replaced the float valve, but not the float, before I had the problem.
 
21 - 29 of 29 Posts
Top