Start issue mk1 16v convertion

Hi,

I have finally gotten far enough for the first engine start. It fires up in the first go but dies instantly after. I does that the next two key turns but then it won't start again (and die again) unless I leave for a few miniutes.

The fuel pumps turns on and I got fuel delivery to the engine, got spark also. The fuel gauge shows that I only have a few liters left in the tank but the car is leveled, can that still be an issue?

The fuel relay is new but I have ordered another one just in case the one I got is faulty.



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A wierd thing that I forgot to mention was that the main fuel pump under the car pumped fuel the wrong way with the new engine and loom (and it did not start at all then). Had to exchange the wires in the fuel pump to get fuel in the right direction. After that the car started but dies directly after.

I wanted to have a look down the tank and inspect the in-tank fuel pump and there was a very small amount of fuel in the hose to the right in the picture. In My expirience there is usualy quite alot of fuel comming out when prying of the hose. Maybe its loosing fuel pressure?

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I was going to say, no/low fuel pressure before I even read anything you wrote. Its certainly an area I'd check. Its quite possible that you don't have enough fuel pressure to lift the mechanical injectors, but enough to fire the 5th injector, thus able to start and run for a few seconds.

Also the fuel distributor may need bleeding, I can't remember if there is a special procedure for this or its just a case of getting it running (maybe on fuel from somewhere else) and waiting for them to clear of air.

I created a short wiring loom which consisted of a plug-on connection to the 5th injector and a momentary switch, so I can fire the injector on command and it was helpful to diagnose a number of issues such as these. It saves needing to squirt a can of easy-start or petrol spray down the airbox otherwise.

The original pump wiring is correct, some one place the new or different pump in backwards wired or spliced wires in wrong.

The main fuel pump has been replaced once but the car has been driven since with the old 8v engine. So I have to take a look att the 16v engine loom that I has spliced in I guess..

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I had the look att the loom but cant find any splicing in regards to the wires that connects to the fuelpumps. I have changed out the fuel relay which where needed when running the 16v, that might make a difference?

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This is how the fuel pump is connected now. The yellow wire connection om the fuel pump is + and the other one is -. According to my measurements the red yellow wire is + which means that it wired up correctly now.

The other piping seems to match the part drawing in the link.
https://volkswagen.7zap.com/en/rdw/golf+cabriolet/goc/1987-44/2/201-69020/

I have ordered a new Bosch fuel pump and I hope that a new fuel pump will solve my problem. I have a feeling that the injectors won't open due to low fuel pressure.

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There's some small filters in the connections, I think to the pump. It is definitely worth checking these (and if they're missing…..having them there).

It would also be worth measuring the fuel pressure for a proper diagnosis before replacing parts, but obviously I appreciate a fuel pressure test gauge or a garage visit is about the same price as a pump anyway…

I have double checked the other pipes and hose connections and the filter you mentioned and its still in place and looks ok. Cant find any other deviations from the original setup so hopefully it will work with a new fuel pump.

Great success! The car has started and runs!

Next problem is the oil varning light blinks in the instrument cluster. There seems to be circulation since I had to refill with more oil after the first start due to filling the oil filter and so on after engine renovation. The oil pump is also new.

Are the sensors incorrectly wired? I just figurer that blue wire goes to blue sensor.. anything else that I can check?

I got a tip from rubjonny to exchange the sensor wires and that seemed to do it! The oil light flashes when the ignition is on but turns off when the engine is started.