I have a 1988 Plymouth Caravelle 2.2 with turbo. All of a sudden it wont start on a hot day. It sits all day and wont start. There is no fuel from the pump. When it is cool in the morning it starts and runs fine. The filter is fairly new. I have checked for fuel from the pump before the filter. I think it might be the fuel pump relay. Thank you for any help you can give.
Last edited by mikeis59 (8/22/2009 5:28 PM)
A loss of fuel pressure can be a lot of things.
Next time it won't start, remove the gas cap and listen inside the tank while someone else turns on the ignition. If you hear the fuel pump buzz for about 2 seconds, and it still won't start, that eliminates a fault with the electrical circuits to the pump (including the relay) being the problem.
If you hear nothing, it could be the relay, but it really requires further testing to be sure. It may be a break in a wire, bad pump, ignition switch, PCM and so on.
If you do hear the pump buzz, then you need a fuel pressure gauge to see what pressure is available at the injectors up front.
Thank you for your reply. You can hear the pump when the weather is not real hot . The car also starts and runs then. But after sitting in 100 degree temp. all day I come out from work and it does not start. As I said I pulled the hose off at the tank when it would not start, cranked it over several times, and there was no fuel coming out at all. I left the car overnight and it started right up the next day. But when I came out from work that afternoon same thing, no start. I had it towed home and now it keeps starting and running. I am afraid to take it to work again though. Towing is not cheap.
Thank you again for any help.
If you're sure the fuel pump is not making a sound for 2 seconds after the ignition is turned on, or while cranking, that confirms it's electrical.
On this one they call it the "auto shut-down relay". It should be mounted above the fender well on the left side of the engine compartment with 4 wires leading to it.
When there is no voltage detected from the ignition switch, the auto shut-down relay kills power to the fuel pump, ignition coil and the injectors. So if this relay was the problem you would also be losing spark.
It could be the relay, and might be worth trying one, but the right way is to check the circuits correctly with a wiring schematic and a test light.
Thank you again for your reply. Right now I am at a stand still. The last 3 days the car has started and ran fine. So its hard to troubleshoot when everything seems to be working. I am wondering now if it could have had a bad ground or bad connection on the relay, because I have had it on and off several times. It also had a dirty connection on the hot wire, which I cleaned. I guess time will tell. I want to thank you very much for your fast reply and information.
Not a problem.
If messing with the relay temporarily fixed the problem. You might want to replace it to be on the safe side (should be pretty cheap).
Remember, if it happens again check for spark also.
I have bought a new relay. I was going to stick it in when it would not start again, thinking that if that were the problem then it would start up right then. But I will go ahead and put it in.
Thank you so much for your help.
It finally reached 100 degrees today and it would not start. I pulled the coil wire and checked for spark cranked the engine and it has spark. So I guess it must be the pump. It just does not make sense to me that the heat would have anything to do with it. It just sits all day without driving. It also has almost a full tank of gas. I checked for voltage at the tank with the key on and have none. I also checked for voltage to the pump from the relay with the key on and have none. I also checked for resistance in the wire from the relay to the pump and that checks out ok. Does the engine have to be running for voltage to be from the relay to the pump. Also no voltage at relay wire to pump with key on when the weather is cool and it runs.All 3 other wires have voltage with the key on.
Thank you again for any input.
Last edited by mikeis59 (8/25/2009 3:29 PM)
It's almost never easy.
Make sure you have 12volts and a good ground at the fuel pump not just with the ignition on, but also while cranking.
I'll touch base with my Chrysler tech buddy on intermittent issues with the pump.
Thank you again I checked for voltage at the pump. It has voltage while cranking the engine even when it wont start when the weather is hot. I also connected a wire from the battery directly to the pump hot wire. I had 12 volts but the pump made no noise at all. However connecting it the same way in the morning while the weather is cool the pump runs. I checked the pump ground wire with ohm meter and it appears ok. Also this happens only after the weather reaches 100 degrees. When its 95 it starts.Thank you again for any help.