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Intermittent fuel pump issue.

3313 Views 11 Replies 4 Participants Last post by  dc8flyer
Hey all, Troy here again with another issue on my 1993 sundance., OK i have no codes and 1/2 a tank of fuel.
so here is what it is doing now and both those times ive had to work on the fuel before. it starts and runs and then out of no where we have no fuel.
so changed pump. started right up. drove for months.
did it again fiddled with the injector, started right up. drove for months.
did it again. this time on the side of the road. I still had the old pump. so i decided that i was going to see if the pump fired at all. it did. it didn't when it was in the car. So on the side of the road in dangers way i swapped the fuel pump again. started up drove it home.
I still had a couple things to tidy up under it before i was done so i back in left it out of the spot a bit. finished and now it wont start. same crap. i changed the filter when i did the first pump.
So now it hits me. every one of these times the car is sitting for at least 30 mins without a battery. plug it up and it starts. I am going to test it again tonight.

Could this be the sign of a failing computer in the car? or am i just really bad at fixing cars. lol (probably.)

Didn't start. pump is not pumping again. last time i had an issue i moved around the relays also. im so very confused. if it were a damaged or exposed wire wouldn't it be more often? could my crank or cam sensor be doing this? where are these sensors located? if these sensors were bad wouldn't i get a code? or would i need the car to run for a bit?
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Well Troy, if you're really bad at fixing cars, you're in good company at least! I had very similar problems on my '95 Spirit. I replaced the fuel pump and relay only to have a completely bizarre no-start. Turns out, I had removed my bulkhead disconnect in an attempt to install a trip computer and not tightened the screw enough, leaving an intermittent connection. It sounds like you've got the same issue. I don't think the Sundance was available with engines that had cam or crank sensors; both the 2.2/2.5 and the 6G72 used distributor pickups. The ECU shouldn't be looked at as a problem until all the wiring checks out. If the car started and ran, it's most likely good (99% chance). Make sure you're actually dealing with a fueling issue too, see if you can get the car to start on ether, carb cleaner, or a little bit of gas. If not, you're not getting spark. Electrical gremlins are a MAJOR PITA and really require a very thorough diagnostic process. Keep at it, and you'll find it.
Thanks for the reply and info. I did try the gas in the tbi and it does start that way. pulled the fuel supply line and no fuel comming to front of the car at all. not even a drip. no fire from the pump. when the pump does fire after its random vacations the car starts right up. is there anything else that could cause this?
I may have to dissasymble the interior and check the wires from tank to dash just to make sure that its not a short causeing the asd to shut down. its the only thing i can think of at this point.
See if you can get the pump to run by jumping the relay terminals going to it. That could help rule out the pump relay. Also check for voltage at the pump with the car cranking. Voltage COULD mean a bad pump; they do very very occasionally fail pretty quickly, but it's a HUGE off chance. That being said, it certainly sounds like a wiring issue to me. You messing with the car moves something enough to make passable contact. I would try probing the pump wires at the bulkhead disconnect. That way you can at least figure out if the problem is in front of the firewall or behind it. If you disconnect the connector, make sure that bolt is in there tight. Close enough really isn't good enough with that, as I've experienced firsthand...
If the car will start with cleaner/gas, the ASD is closing. The ASD completes the circuit to the fuel pump relay as well as to the primary on the coil. If the ASD isn't closing, there's no possibility for spark. The questions you want to answer are:
Is the fuel pump relay closing, reliably, every time? If it is, is the power going INTO the relay and coming OUT the other side? If the power is coming out, is it getting to the fuel pump? The way I would go about this is to wait until the car won't start, and then start probing, jumping and testing. Try to simulate as many components of the circuit as you can. Clean and check all connectors. Jostle the car around and see if you can get something to change (i.e. go from starting to not starting or vice versa), and then see if there's one specific area that you can move to cause a change. Like I said, wiring is a MAJOR PITA.
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Wanna know the cool thing about safety relays? they save your [I should have my mouth washed out with soap for using such terms]. lol. I really doubt this was the root of the problem but the fuel lines were loose at the throttle body. that might have triggered the asd like it is supposed to. but the thing is the loose hoses would not have been the issue a week ago. the car is running for now. ill get back if it does it again.
The ASD really has nothing to do with automatically shutting down the engine. It has no way of detecting an unsafe or potentially damaging condition; the electronics just aren't that sophisticated. It's really more of an anti-run on relay than anything else. It kills fuel delivery and spark to ensure that the engine shuts down when you tell it to. Chrysler often uses weird names for things or holds over names that really no longer describe the function of the component or system; this may be one of those cases. While loose fuel lines are certainly a safety hazard, I still think you have an electrical problem.
Actually, its main purpose (ASD = "Automatic Shut Down") is to kill the ignition and fuel pump if the engine is not turning. This is to prevent fuel from pumping in the event of an accident and causing a fire, where the ignition is still on. But yes, it cannot detect loose fuel lines or changes in fuel pressure or act on them.
ok having this problem again. i ran a wire directly to the pump. it works good. but wont start. the wire diagram i have shows nothing between the power and the pump but the ASD.

what do i check now?

The car surges when the head lights are on when it is running. sometimes the radio cuts off. the alternator was tested good and battery is good. could all these problems be from the same place? maybe a bad ground?
I had a similar issue but I was getting a code on my 1987 600se.

The car would just shut down. I cranked until the battery died then had it towed home. I changed out a number of parts but I believe the issue was the contacts to the injector cap, the wire from the injector cap to the connector, and the connector plug.

I spliced a new connector plug as the wire insulation was brittle and parts of the insulation had fallen off exposing small areas of wire.

The wiring from the connector to the injector plug also showed insulation having broken off and was making contact to the throttle body. I believe this was the main issue as vibration could have forced a grounding issue at times and caused the car to just shut off. At first I used liquid tape to cover this area of concerned and it seemed to work. I eventually replaced this connector with a spare.

The injector contacts inside the connector cap were also a bit loose so I gently tried to close them up a bit. I then used a tiny amount of dielectric grease and put it all back together.

I believe the above was the main issue but I also changed out the alternator, plugs, wires, rotor, distributor cap, pickup coil, and coil.

Every time you disconnected the battery you reset the computer faults and I think that helped restore the vehicle to drivability until it shorted out again.

Hopes this helps.
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While I'm here, does anyone have a 1987 Dodge 600se, 2.5 service manual they wouldn't mind sharing.

dc8flyer- The factory issued service manuals (you'll see them referred to on here as "FSM"s or Factory Service Manuals) in sets of three for the FWD cars. There was a manual for engine, chassis and body, one for electrical, fuel and emissions and one set of factory wiring diagrams. Here's a link to all three: . The full set is nice, but if you just want the engine manual, there's one listed here: . I have a full set of 1992 manuals, but there were significant changes between '87 and '92. I can still scan you a few pages from mine and email them to you if you would like, just PM me.

troy-- Are you sure your fuel is getting to the injector? Try disconnecting the fuel lines at the TB and running the pump with a bucket to catch any gas that comes out. Also do a pressure check; I don't have my manual in front of me, but I think the pressure should be somewhere in the 16-18 pound range for TBI. If you're getting fuel to the injector and the pressure is good, the next step would be to connect a 12V lightbulb across the injector terminals in the cap. If there's power getting there, the issue is in the injector itself. If there's no power at the injector, there's a break somewhere or there's something wrong with the ECU. I only mention the ECU because of the surging issue. The surging COULD be because of a failing voltage regulator, which lives in the ECU. If one portion of the ECU is POSSIBLY bad, it's not too much of a leap to assume that the fueling issues COULD be related (bad solder joints can be abundant in older Chrysler electronics, depending on the supplier). The reason for all the capitalization? I find that many, many people equate the computer being a potential, but unlikely suspect with the computer needing replacement. Nine times out of ten, it's a waste of money. However, because you're potentially dealing with two circuits that run through the ECU, I think that the computer might actually be at fault here. You'll need to do a charging/voltage regulator test as described in the FSM. If the regulator tests bad, I would replace the ECU before pursuing any of the other issues. Worse comes to worst, you ended up replacing a part that was actually bad. The most important thing is a thorough diagnosis.
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dc8flyer- The factory issued service manuals (you'll see them referred to on here as "FSM"s or Factory Service Manuals) in sets of three for the FWD cars.

Thanks for the links.
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