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Background: 91 240, LH 2.4.
Initial issue: crank no start, not trying to catch. The car had 1/2 tank of gas in it. Could not hear the fuel pump when turning ignition on, but could hear it when jumping fuse 4 to fuse 6. Pulled the relay out, saw there was infinity between terminals 85 and 86.2, in either direction. Also when I jumpered fuses 4 and 6 the car started. Replaced the relay, the car started.
Two days later, again crank no start, but this time the car is trying to catch. Jumper between 4 and 6 did not make any difference. The street was noisy so I can't tell if I could not hear the pump because of the street noise, or because the pump was not running.
Towed it home, next day it started and ran fine. I am suspecting the in-tank fuel pump, but need help verifying it. The car now has a full tank of gas, if that's significant.
1. There is infinite resistance between the black wire and the brown (ground) wire of the fuel pump. This is bad, right? (There is about 60 ohms between the gray wire - I assume the sending unit - and the brown wire).
2. When I turn the ignition on, there is 0 voltage on fuse 4. Should there be battery voltage?
3. With ignition on, I cannot hear the fuel pump. With fuses 4 and 6 jumpered, I can hear the pump.
4. When I start the car, there is good voltage (13+) on fuse 4, and on the red-orange wire that connects to the black fuel pump wire. Why is there voltage now, while there was 0 voltage when the ignition was on but the car was not running?
5. The new relay shows infinity between terminals 85 and 86.2, in either direction. This is bad, right? I am almost certain I tested this relay before putting it in, and it showed about 2 ohms between those two terminals.
So, to summarize, it appears like the new relay is bad after two days of running (item 5 above), and the in-tank pump is bad (item 1). Two parts bad at the same time, one of them brand new, something is not right with my reasoning.
What am I doing wrong?
Thank you in advance.
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A bit more info on item 3. When I take fuse 4 out and jumper fuse 6 to the left terminal of fuse 4, I hear the pump (main pump?). When I jumper fuse 6 to the right terminal of fuse 4, I cannot hear the pump (in-tank pump?).
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If you remove fuse 4 & jumper the right hand side of fuse 4 holder to fuse 6, you should hear the in-tank pump run. If you don't then it is not functioning. The car usually will run in this condition but it makes the main pump work harder and eventually fail. You may have reached this point.
I usually can tell when the in-tank pump stops working as the main pump gets noisier. I have a '90 240 that has the original main pump in it going on nearly 260k miles. Twice the in-tank pump failed and I noticed just from the fact that I could hear the main pump running while I was driving. Both times fixing the in-tank pump got the main pump running back to it's old quiet self.
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Thanks, you're describing what I am seeing (or hearing, or not hearing) - jumper from 6 to the right side of 4 results in no sound. The car has a bit over 260K miles on it, and as far as I know the pumps are original.
Still unresolved is whether the relay is bad as well.
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Hi,
I don't know if you did this or not, To test the relay.
Open up the relay and look at each side of it. Do the contacts look ok as not burnt black?
There are two sets or one unit on each side..
You can push either one down to make the contacts work.
You can also use a rubber band and small pieces of wood to hold each one down individually.
I keep Popsicles sticks in my tool box because they can help you lick other problems. (:-)
When cranking the engine, observe if both are closing.
The ECU then in turn grounds the injectors so the power will flow through them.
Same goes for the pumps.
This is why Art wanted you to put a test light on the orange wire under the rubber boot of the AMM.
The orange wire power more than just the injectors but even the AMM.
The ICU gets a signal from the distributor, when cranking or running.
That turns on the ECU that turns on the relays. ITS All about sequences.
You said the cars runs with the pumps jumpered? So that puts all the other stuff working and you are back to pumps or a relay circuit malfunction.
Grounds or a Non -operating ECU circuit can be a problem.
You have to isolate it down to an area of either circuit or broken parts going out to the pumps.
Like Michael says, powering up each pump directly helps diagnose the pumps.
I hope I shed some light on what you need to investigate.
Phil
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Two outcomes, and a couple of observations.
1. The fuel transfer pump was bad. Infinite resistance between ground and black wire, confirmed by infinite resistance between the two terminals of the pump once I got it out, was the clue. The normal resistance is as I recall about 600 Ohms.
2. The relay was good. When testing one of the coils, the one that is in series with a diode (terminals 85 and 86/2), one needs a meter that has a "diode" mode. Just measuring resistance through a diode may not put enough voltage through it to register anything. When I switched my meter to this mode, it showed about 670 ohms. This is also confirmed by the fact that I get good voltage on the pump when I crank the starter.
As far as testing the fuel transfer pump, a couple of things I would have found to be of value if I had known them.
First, the pump is plenty loud. This is based on the behavior of the Delco pump that I put in, which I understand is the OEM pump. In a wagon, with the 3rd row of seats out of the car, even with the fuel pump access cover on, I could hear this pump at least as loudly as the main fuel pump.
Second, when connecting a jumper to the right terminal of fuse 4, I could see a considerable spark. This is not full proof, because a pump can jam and still conduct, and because the O2 sensor heater is connected through the same fuse. In my case the pump was not conducting, and the O2 sensor uses much less current, so the spark was pretty small with the bad pump.
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"First, the pump is plenty loud. This is based on the behavior of the Delco pump that I put in, which I understand is the OEM pump. In a wagon, with the 3rd row of seats out of the car, even with the fuel pump access cover on, I could hear this pump at least as loudly as the main fuel pump."
To me, the hum of the tank pump in a wagon is a comforting sound, although I have some idea why it might be so loud after a replacement compared with what a new car owner might tolerate driving off the dealer's lot.
However, you shouldn't hear the main pump at all from inside the car. Yes you probably did hear it and become more aware of it when the tank pump was not working, but the main pump should run smooth and nearly silent.
In The Tank
--
Art Benstein near Baltimore
As told by G.Downs III:
After years of hiding the fact that the love is gone, the last child moved out of the house and
Mom and Dad announced they are getting a divorce.
The kids are distraught and hired a marriage counselor as a last resort at keeping the parents together.
The counselor works for hours, tries all of his methods, but the couple still won't even talk to each other.
Finally, the counselor goes over to a closet, brings out a beautiful upright Bass, and begins to play.
After a few moments, the couple starts talking.
They discover that they're not actually that far apart and decide to give their marriage another try.
The kids are amazed and ask the counselor how he managed to do it.
He replies, "I've never seen anyone who wouldn't talk during a bass solo."
And for that, the counselor gets $200/hr, and doesn't have to join the musicians' union....
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Hi,
Just some innocent questions that comes from wonderment!
Are you listening from the gas tank fill pipe with the cap off?
Some people, with old ears, use a short piece of garden hose stuck through the unleaded flapper.
The pump inside will be really quiet, if the tank has a lot of fuel in it.
The pump itself sits in a baffle that looks like a stainless steel bowl is in the very middle of the tank. This too can block some the sound from getting up to the filler pipe.
Just your thinking of very old pumps is a valid thought.
The in-tank pump usually does not out last the main pump.
Plus there is a rubber hose connector in between that fails too!
When I have my car up on a car lift the pump it possible to listening it from directly beneath the very center of the tank.
I know, doing a crawl under the car does not look or feel cool, but hiding in the trunk, to change out that pump that might be working, could make one hot! (:-)
Phil
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I prefer to unplug the pumps and use jumper wires directly to a 12V source to test the pumps. Once you’ve confirmed they work then turn your attention to fuses/wiring/relay. Keep in mind if the short discharge hose on the in-tank pump has disintegrated, and they all do, the pump can run without pumping much of anything....
--
82 242-6.2L; '17 Mazda3; '16 Crosstrek
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