I am the original owner of a 1983 VW GTI. It has now become a classic which I enjoy very much. With 85000 miles, it runs well. Suddenly, it has developed a hot start problem - after running for a while, if I stop and let it sit for about half an hour, it is very hard to start if at all. Once it cools down it will start. I have checked the auxillary air regulator, cold-start valve, and thermo-time switch. Found no problems. Replaced the ‘O’ ring seals in the injectors, and replaced a very expensive control pressure regulator when I found the OHM reading to high. Does anyone have an idea what the problem might be, or can you point me to a mechanic in the Washington, D.C. area who knows these old fuel injected Volkwagens very well?
Mk 1 eh ? Nice car, had a 1a 1800 years ago, great little car.
I used to know my way around the Jetronic system pretty well since it’s also used on Jaguar, but that was long ago. An absolute must is to get a copy of this : http://www.boschtechinfo.com/index.cfm?event=product.menu.search&format=Service%20Guide
I have one but it’s in London…and I’m in the US, so not much help.
The K-Jetronic system was used on many Euro injected cars during the early 80s, Peugeot, Mercedes etc try googling “K-Jetronic Troubleshooting” and you will pull up some trouble shooting guides. Bosch used to have a good online guide, but I just checked and the link is dead.
InterJect is a good reference I used to use for Jaguar : http://www.users.bigpond.com/INTERJECT/KSITEPLN.HTM#K-JETRONIC%20schooling
Two possibilities, although normally step one is connecting the special fuel pressure tester and checking system and control pressure.
One could be a fuel injector (or two) leaking off. This could be checked by removing all of the injectors, allowing them to dangle, and then jumping the fuel pump relay to pressure up the system. Watch the injector tips and note if a drip appears.
There is a special tool used to clean and test the injectors but this is generally out of the park for the DIYer economically. You might consider removing the injectors and having a VW dealer perform this service. It should not take more than an hour with the injectors out.
Another possibility is the fuel accumulator. In theory a fuel accumulator problem will not cause a hot start problem but in practice it can happen.
I would say look at those injectors first because that is a pretty common occurence with CIS. Hope that helps.
(I would add that if you inspect the injectors for drips you should also check the spray pattern. With the pump still energized and the intake boot removed, take a pair of pliers, grasp the bolt head in the center of the air plate and slowly (and gently) pull upward. This will cause the injectors to spray. If the pattern is not cone-shaped and erratic then that is yet another reason to run the injectors through the cleaner/tester.)