1980 Mk1 GTI

[Lima]

Do a serch on vortex for "hot start relay" if that is no avail message me here and I will scan and email you the wiring / relay etc. It was a problem with the 8Valve cars for ages ( heat soak from the engine once parked) has happened to me only a few times in the madness that is summer.

For an instant fix, remove the rubber banjo over the metering head, lift the air plate with pliers while cranking the engine, it will allow the fuel vapour to exit the injectors til fuel liquid comes out allowing the engine to fire. reassemble and drive. tooling is a screw driver and a pair of pliers as well as another person.

Thanks for those tips!

[mikinoz]

Are you saying that this is a retrofit relay? I'd appreciate the diagrams.

[Lima]

Here's one I have found, not sure if it's suitable: VWVortex.com - Starter relay for heatsoak problems

Although the symptoms listed in that thread are different to what my car suffers (see video below for my car).

From the thread above: "Symptom: You turn the key and nothing happens. Nothing. Not even a click. The voltmeter does however show you sucking major current."

Video of my car's symptoms:



---------- Post added at 08:36 PM ---------- Previous post was at 08:24 PM ----------

Here's a good overall reference on K-jet too...

The Mk1 Golf Owners Club: You have been blocked

---------- Post added at 08:41 PM ---------- Previous post was at 08:36 PM ----------

Also from vwgolfmk1.org.uk

K-Jetronic: Troubleshooting Symptoms

K-Jetronic is a mechanical system: the fuel is continuously metered in proportion to the quantity of air drawn in by the engine. The K-Jetronic system was installed as Original Equipment in series production vehicles in the years 1973 through 1995. Since then, the K-Jetronic system has been only of significance for repairs and maintenance.

--

Symptom: Engine does not start/starts hard when warm

Cause : Remedy

Leaks in air intake system (false air) : Check air system for leaks
Sensor plate and/or plunger not moving freely : Check for free movement
Air flow sensor plate stop incorrectly set : Check and reset
Electric fuel pump not operating : Check pump fuse, pump relay and pump
"Warm" control pressure too high : Test pressure
Fuel system leakage : Inspect fuel system for leaks
Injector leaking, opening pressure low : Check injectors on tester
Injected fuel quantities unequal : Check for equal fuel quantities
Basic idle setting incorrect : Check and adjust CO level

---------- Post added at 09:00 PM ---------- Previous post was at 08:41 PM ----------

Some more interesting reading, K-jet related, but not specific to Golfs: K-Jetronic Hot-start Problem on M110-984 - PeachParts Mercedes ShopForum

---------- Post added at 09:06 PM ---------- Previous post was at 09:00 PM ----------

Another K-jet reference: K-Jet.org | K-Jet Debugging Guide

[mikinoz]

This is what I am keen to investigate.

"You shut the engine off hot, and it cools down, but not enough to activate the cold start mechanisms. The fuel in the system contracts as it cools leaving a vacuum in the system. For some reason, it takes a lot of cranking and fuel pump running to overcome this and get some fuel to the cylinders.

So the solution was a quick shot of fuel from the cold start valve when the starter cranks."

[roccodingo]

Hot start problem was due to the heat soak from the engine.

Fuel lines from metering head pass to the back of the engine where the heat from the exhaust / inlet manifold create a hot spot at the rear side of the valve cover. This causes the fuel in the injector lines to vapourise ( fuel isnt flowing cause the engine has stopped running) vapour is compressable, liquids are not. When the engine is attempted to restart, the vapour must be purged from the fuel lines before the car will run consistently. From memory a relay is wired in to bleed fuel and if any vapour from the cold start valve to get the engine to fire . Latter VW's have a temp sender attached to the rear of the valve cover to operate the radiator fan in a "run on mode" to move air through the engine bay, hopefully lowering the under hood temps when car has stopped.

Liam, if your car has only run for a few minutes, switched of then attempted to be re started in 30 mins, I would think you dont have enough heat in the engine bay to cause the heat soak the hot start pulse fix is designed for. Does the fuel pump operate when you try the re start ?? I think its definately fuel related as when it catches its a bit missy.. I can see on the video In all cases when you crank the tacho gives that little bounce, I guess thats confirming there is an electrical pulse coming from the coil.

Have you had the system pressure checked, k jet is pretty reliable but when it wants to be a bad boy it'll give you the sheetz. Pressure and fuel flow have to be set in the operating parameters. The cabrio is going in tomorrow for a cold start issue btw.. giving the missus grief !!

I will scan the manual tomorrow and send it over, pm me your email addy , or yours Mick

[Vinda76]

I agree with Grant. My first thoughts were that the system isn't holding pressure once the engine is switched off, fuel under pressure has a higher boiling/vapourisation point. Originally there would have been two non-return (check) valves (one after the pump, one after the filter - I've read that the one on the filter was removed by vw in some cases during early services, no idea why). Leaky injectors will also cause pressure drop, which is probably more likely than faulty check valves and easier to check.

[Lima]

Liam, if your car has only run for a few minutes, switched of then attempted to be re started in 30 mins, I would think you dont have enough heat in the engine bay to cause the heat soak the hot start pulse fix is designed for

Sorry Grant, the video may be misleading. After the initial start I did go for a drive, maybe 15-20 minutes from memory. And the subsequent non-starts were after the car had returned from that drive. So there should have been sufficient heat soak to meet the symptoms being discussed.

If I move the car to wash it, or just a quick spin around the block, it will restart no problems.

The first post in the PeachParts Mercedes link above is pretty much a perfect description for my car. The only difference being it can take more starting attempts and/or a longer period of rest before it will eventually start. When it does finally start it runs really rough for 15-30 seconds, before settling to a more appropriate idle speed.

[mikinoz]

I will report back once I have had time to go for a drive, problem is having the time to do it when I might get stuck somewhere!

[Lima]

Don't forget you only have until Wednesday 9 May (technically) and I will send you the new rego sticker as soon as I have it, haha. Although, 12 months rego has been paid for so you'd probably be right anyway I guess.

[roccodingo]

hot start pulse relay wiring.



Unsure of the actual relay part number but try google .