I have a Saturn LW3 station wagon. For the past few months it has randomly failed to start (it cranks/turns over but it acts like it is never getting any fuel). I took it to a good mechanic but he could not replicate the problem. The mechanic did a scan and there were no error codes. I waited until it happened again and I had it towed to the mechanic. Finally it would not start for him either. He explained to me that he tested it and inexplicably no power was getting to the fuel pump. He also explained to me that it was not the relay (I forgot the reason he gave for this, but like I said, he is a good mechanic). He was baffled but needed to get to other cars that were ahead of me. So the next day he went to check it out and it started right up.
Considering there are no more Saturn dealerships with mechanics that work on these cars all the time, does anyone out there have any insight on this matter?
I’m not a Saturn guy, or ever wanted to be, but there could be any one of a number of reasons for no power to the pump. Since I do not have a schematic in front of me just consider this theory.
The relay as mentioned. Usually if a relay is failing it’s because of an aged fuel pump and/or clogged fuel filter. This causes the current draw of the pump to spike up and this means more current through the relay contacts; meaning much more heat and burned contacts.
Usually the relay trigger is grounded through the ECM. Lack of a ground when the key is first turned on means a poor wiring connection between the relay and ECM or a faulty ECM circuit.
Lack of a ground after some seconds of cranking can point to a faulty ECM, faulty wire connection as in the above, or a fault with the electronic ignition. (The ign. provides a pulse to the ECM which uses that pulse to trigger a ground for the relay and close the circuit to the pump.)
The mechanic states there is no power to the pump. How did he determine this? When the key is first turned on there will only be power provided for a couple of seconds. After that the power will disappear unless the engine is being cranked over by the starter motor.
If he checked for power after the key had been left in the RUN position for a while then there would be no power showing on a test light or VOM. That would be normal. Hope some of that helps.
The mechanic MAY have just listened to or for the relay to click…well that’s HALF of what a relay does…and there are ways to test it… When you hear the click on a relay it is TRYING to make a new connection via contact points…you THEN need to see if those points are clean and able to carry current…sure it clicks…but is there continuity between poles 30 and 87 now? Did he check that? or just listen to the relay click? All good questions
I’ve seen MANY a “mechanic” tell me this or that relay is working…and then when I get it in my hands…I say…really? If you deal with these things AND know what is happening in the components…there is NOTHING you cannot remedy/fix…that’s how I go about things…
Replace the relay yourself and be done with it…feeling adventurous? Take your relay apart and see what I am talking about…fix it yourself even and re-install it… Now THAT will make you feel good… I can use a pack of matches to fix those relay contacts …LOL…that’s my Grandfather coming out in me .lol
Sounds like you have all the elements to solve this issue…pump not getting power…PULL the relay and GIVE IT POWER…still none? Broken wire then…but go in steps…I’d stop right at that relay and see what its doing…its key…