I posted this two weeks ago. 186 viewed it, nobody commented. This is the original post and what I did is at the end.

Starts cold no problem, but after engine warms up and I go into a store for 10 or 15 minutes, when I come out it won't start again. When its working properly I can hear the fuel pump relay click and the pump prime for a couple seconds before I start it, but after the engine is warmed up the relay won't prime and the car won't start. If I am patient and sit in the car for another 20 minutes or so, the pump finally primes and it starts again.

I've checked and cleaned contacts on the relay and fuse as well as the fuse holder. I checked and cleaned the secondary fuel pump and filter. I checked the fuel pressure regulator - no gas in vacuum hose. What could be causing this problem? Also, there's no vacuum sound when I remove the fuel cap... shouldn't there be?

A friend told me he had the same problem and he just installed a switch on the dashboard between the fuse to the pump in order to manually activate it, but I'd rather solve the problem than create a work-around. Any help here would be greatly appreciated.

Here's what I did: I put a jumper between fuses 4 and 6 to bypass the fuel pump relay. Now the car starts every time. However....

Before I placed the jumper I had an error code 2-3-2 showing a fuel to air ratio compensation. I cleared the codes after jumping the fuses and when the Check Engine lit up again, I now get a 2-1-2 error indicating a faulty oxygen sensor. Any ideas yet?

 

What kind of car are you working on?

 

1992 240 - After I jumped the two fuses mt battery was dead the next morning so I removed the jumper. If I'm going to use a work-around it has to be a push-button. I'd much rather know why the problem is happening and address that - not put a bandaid on it. Thanks for getting back with me.

 

Hello Mr. Baade,

Sorry to hear of the issue with your 240. Hot start issues can be very troublesome to diagnose. Can you please tell me the VIN and if the car has Bosch or Regina injectlon. Thanks.

Dean
Customer Service
eEuroparts.com

 

VIN - YV1AS8810N

Bosch

 

thanks...

Have you cked your fuel pressure at the rail when the car is hot? I am assuming that the engine is cranking fine when hot but will not start. Have you cked for spark when this cranking but not starting issue is occuring?

Dean

 

Never would have suspected this. I drove the car on a very hot day, 104 degrees, and it overheated just going up a hill. I suspected the thermostat, or a possible radiator problem, but a friend said, "maybe your radiator is just clogged up with bugs and dust... let's see if we can clean it first." So I removed the fan shroud to get the water hose down there and squirted water through the radiator fins. Pure mud began to pool up on the driveway! I continued spraying until only clear water dripped from it and now the car doesn't overheat going uphill AND the warm start failure problem went away,

I hope this helps others with similar weird problems. Thank you all for your help too.