1988 Volvo 240 Dying on Long Drives

Hey all, I've been tracing a problem with my 240 for a while now. It's a mostly stock LH2.2 car. Recently I've replaced fuel filter, done the upgraded IPD in tank kit, and done a basic tune up. Whenever I take it on road trips it seems to cut out and eventually die. It acts just like the fuel pump relay is going bad but it did it with a brand new URO relay and a brand new Duralast relay. It also did this while fuses 4 and 6 were jumped. I know that the relay also sends a signal to the ignition so while I was stranded on the side of the road I made the three leg bypass harness to completely get rid of the relay, which got me another 1.5 hours to my destination. Now I'm 2.5 hours from home and hoping to figure this out before I leave saturday. Any ideas?

I was thinking bad wiring could be causing the relays to burn up prematurely by putting too much load on them. Or maybe the upgraded fuel pump is too much for them to handle?

Also maybe this is normal, but I did notice that for whatever reason my car will still run without fuses 4 and 6 in place! I thought that would completely cut power from the pumps. What am I missing??

So I did some more research, apparently fuse 6 only powers the main fuel pump in non US spec cars in 1987 and 1988. Supposedly that writing on the fuse box cover is for KJET cars. That explains why it will still run without fuses 4 and 6 but not why it keeps dying on the highway.

“ It's a mostly stock LH2.2 car. ”

Well, the non stock parts might make a difference...

Nickagriffin said:

So I did some more research, apparently fuse 6 only powers the main fuel pump in non US spec cars in 1987 and 1988. Supposedly that writing on the fuse box cover is for KJET cars. That explains why it will still run without fuses 4 and 6 but not why it keeps dying on the highway.

Click to expand...

Fuse 6 is not used for the main pump. It get power directly. No fuse. Fuse 4 is used for the in tank pump, so removing fuse 4 will disable the in tank. If you need a diagram, I have it here: https://www.240turbo.com/fuelpumprelay.html

It is possible that your in tank pump is not running. It is certainly not with the fuse removed.
A large pump will not overload the relay. Any burning or melting there is the result of a poor or corroded connection at the pin used for power. It needs cleaning and some conductive grease will help.
Dave

dbarton said:

Fuse 6 is not used for the main pump. It get power directly. No fuse. Fuse 4 is used for the in tank pump, some removing fuse 4 will disable the in tank. If you need a diagram, I have it here: https://www.240turbo.com/fuelpumprelay.html

It is possible that your in tank pump is not running. It is certainly not with the fuse removed.
A large pump will not overload the relay. Any burning or melting there is the result of a poor or corroded connection at the pin used for power. It needs cleaning and some conductive grease will help.
Dave

Click to expand...

Alright. Maybe I did something wrong when putting in the upgraded IPD pump. Thats the only real modification it has. I?ll check that out tonight

When this happens does the car run after sitting for awhile? I would check for spark when this problem is happening. Could be something in the ignition like the hall sensor failing. Also check for injector pulse when cranking.

dl242gt said:

When this happens does the car run after sitting for awhile? I would check for spark when this problem is happening. Could be something in the ignition like the hall sensor failing. Also check for injector pulse when cranking.

Click to expand...

Yes, it does run after sitting for a while however whenever it dies I mess with something before trying to start it again. For example when it died on the way to where I am now, I pulled over and did the fuel pump relay bypass before starting it again. I guess this means I need it to break down again before testing to see if just letting it sit will help anything.

I'm guessing that you're thinking it could be vapor lock?

It's hard to fix an intermittent unless it's happening. When it dies you'll want to be ready to troubleshoot to figure out if it's ignition or fuel, or timing. Figure out what's missing. Something like a sensor or engine electronics can become temperature sensitive from running a long time.

How is the air thermostat inside the air filter housing. Is the engine breathing the hot air from the exhaust manifold all the time?

dl242gt said:

It's hard to fix an intermittent unless it's happening. When it dies you'll want to be ready to troubleshoot to figure out if it's ignition or fuel, or timing. Figure out what's missing. Something like a sensor or engine electronics can become temperature sensitive from running a long time.

How is the air thermostat inside the air filter housing. Is the engine breathing the hot air from the exhaust manifold all the time?

Click to expand...

So after no breakdowns for a while, I put one of the supposedly bad FPR's in there and it hasn't broken down on me once. The only other thing I did was open the intake box where the filter is to see if that would allow it to breathe cooler air. I just checked the intake box and the thermostat was in fact wide open after driving the car around and letting it heat up completely. I guess that was the problem?

That surely contributed to the issue. That hot air is no good. I run cold air all year by running the hot air port to the front of the car on the right near the headlight. Dual cold air has gotta be good for 50hp!