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Fuel Pump Issues

I'm gonna be lazy and not search and I don't wanna hear it so :flip: A lot of the newer member won't know me I'm sure but I've been around quite a while, just busy as hell.

Anyway, my fuel pump is intermitantly not working. Tonight after shaking the car violently while driving, it ped out right after I filled my nice big gas tank, and backfired and wouldn't start. That good ole whiny fuel pump noise wasn't there, so it was no mystery why.

Called the tow truck, went in and had some dinner (gotta loe truck stops) and waited. Tow truck shows up, I put the key to on to loosen the steering to push it and what do I hear... the fuel pump and she starts up no problem. I had it towed anyway just in case and of course now I'm looking at dropping the tank.

So in all of your opinions do you think I should say screw it and put in a new pump or is there a way to test it while the tank's down? Pump was replaced in 9/99 by a previous owner, I have a MFC of AIRG and a Part Number of E2100H which mean nothing to me and the description simply says fuel pump.

I welcome any suggestions

Fuel Pump Issues

Reply #1 –
sounds more like a bad conection then a bad pump..

check the useual stuff fuel pump inertia switch,relay and mainly the wiring.. back in the day mine did the same thing and it turned out to be a bad conection and it was the main hot to the relay for the pump which is a solid yellow wire. a little larger gauge wire then most of the wires about 12 or 14 gauge. i don't know if it the same color for the T/birds or mustangs. and runs on the same side as the ECM. right next to the ECM and has a factory spade conection  and thats where i had the failure at the conection i tuged on the wire and it fell right out of the spade..

Nick
Quote
there's only about a half a dozen man made objects that are herd by the human ear below 40Hz,a pipe organ,thunder,the space shuttle lifting off,a jet airplane taking off or landing,a large canon,an atomic bomb ignited in your back yard and the heat wave afterward oh wait you would be dead so you would'nt hear it scratch that!,and maybe beating your hear against a wall less then 40 times a second..rap music is'nt one of them!thats 40-60Hz@100+db the moving air is under 40Hz

Fuel Pump Issues

Reply #2 –
I've thrown the inertia switch before and it's the first thing I checked. I'll check the wiring tomorrow, can't say my electrical system has been cooperative lately at all... My brake light problem was from a connecter going to hell so it very well could be and it'd be preferably to emptying and dropping a full gas tank

Fuel Pump Issues

Reply #3 –
Wowsers!  Look who it is!


You may try bridging the two connections at the self test connector when it fails again.. Jeremy can point out wich ones to connect.
One 88

Fuel Pump Issues

Reply #4 –
is there a fusible link along the way somewhere?



PS:OPETH!!!
1987 TC

Fuel Pump Issues

Reply #5 –
Truthfully, I would replace it.

I replaced my leaking tank and didn't replace the pump. A couple days later I got the bucking bronco upon acceleration then it cleared up and a couple miles later I coast right through a busy intersection. It was dead.

The fuel pump worked the next day after I got it towed home. But  I replaced it anyways and I never had any problems since.
2005 Subaru WRX STi|daily driver

Fuel Pump Issues

Reply #6 –
Wow...Crystal's back...it must be Christmas. ;)

Quote
Tow truck shows up, I put the key to on to loosen the steering to push it and what do I hear... the fuel pump and she starts up no problem.

Ahem...perhaps you inadvertently solved your problem...think 'ignition switch'...

Fuel Pump Issues

Reply #7 –
i suppose if this were my problem,, id be kinda pissed if the fp was that new and failed.  Hows come the 20 year old bosch ones lasted this long?

I could suggest what the Shop manual says to do and it might be in your best interest to do so cause it will verify if the pump is actually going bad or not.  They say to install a fuel pres tester to the shrader valve and secure the guage to the windshield with tape.  Drive your car and observe the fuel presure does not drop below 30psi during the "LABOR" of the engine between shifts.  If it does fall below, replacement is gonna have to happen.  Driving the car under a load is really the only way to simulate the problem.

I does sound like an electrical issue but here are a couple diagrams to help out.  Primary page to focus on is page 54.  Page 55 shows that power splice "s532" on the top and is the source or "source splice" of power for your fuel pump relay located at lower right hand front of engine. 

Go to the test connector and ground out the tan/light green wire.
turn the ign switch on, this supplies power energize the EEC Relay.
The eec relay will now deliver power to the coil of the Fuel pump relay. (stare at it for a min and you'll see what i mean)
the fuel pump relay will get its ground from the eec.
the pump relay will energize if the inertia sw is closed and the eec pin 22 supplies the ground.

The fp relay yellow fuse link wire will send power to the pump directly if all works as planned.

Your best hope is that the fp is not working while you troubleshoot.  This way you can isolate the issue without even getting dirty.
Perhaps checking the fuse link connections up at the starter relay would also be an option while troubleshooting.


With the tan/light green wire grounded and the ign sw on, you can hear the pump run.
If you do not hear the pump run,, ground out the same color wire at the relay in the trunk. 
if the pump does run, the eec or the chassis wiring (tan/lg)leading to the relay is defective.
If it does not run still, then apply a 12v power leg to the pink/black
if the fp runs, the relay is defective.
if the fp does not run, its the pump.

Fuel Pump Issues

Reply #8 –
Fuel pump.
Had the same thing happen to me,would run fine then would not start,no noisy pump or signs,chased every wire and the inertia switch.
Turns out it was a bad pump.

Fuel Pump Issues

Reply #9 –
Thanks for the info guys... looks like I have a good amount of diagnostics to run

I'll also add in that dropping the tank is something I should probably do anyway, during my suspensions classes this past semester I had plenty of time to roam around the underside of my car and learned 2 very not fun things...

1. The lower passenger front rail is basically rotted away
2. One of my gas tank strap mounts is totally rotted away, so my big mammoth tank is being held up by 1.5 straps. I have some welding to do up there so while the pump being bad would suck, I ordered one just in case and will probably return it if not needed. This is not really at all what I wanted to do over my vacation :toilet:

Fuel Pump Issues

Reply #10 –
the 3.8 supercharged fuel pump is 90lph stock.  Better than the bosch 60lph.  the sc pump is what i have now and my output presure before the fpr is actually 110. Much better than its rating.  Its about 42 dollars i think.  Make sure it comes with the little short section of hose that is about 3'' long.  mine did not.  Dont reuse that old one cause it may also be cracked.

Fuel Pump Issues

Reply #11 –
Well, I blew half my day looking for a new o-ring for my fuel pressure tester. At least in the yard it holds steady at about 42, the line's too short to drive and watch it, so tomorrow I'm modifying it to actually reach and hopefully get some of this electrical stuff looked at.

Took her for a beating around the block and she's still shaking a bit on heavier acceleration. Gonna throw in a new fuel filter for the hell of it, couldn't hurt...

Fuel Pump Issues

Reply #12 –
Quote from: CougarSE;120348

You may try bridging the two connections at the self test connector when it fails again.. Jeremy can point out wich ones to connect.



Grounding the lower right EEC test connector connection will run the fuel pump continuously with the key "ON". This can be used in situations such as when you fry parts of the EEC and it won't run the FP on its own.


I had symptoms similar to yours once. The car would run, then sputter out and die. After 5-10 minutes, it would start and run like nothing happened. After 3-4 times, it finally quit for good. A new FP fixed her right up.

Fuel Pump Issues

Reply #13 –
89-93 f150's have an external high presure fuel pump,,just fyi.

Carter part number P70199 external FP 95psi/@90gph crosses over to Kragen pn EP7107 for 80 bux or so.

if external turns you on.,, i personally think its a great idea.  for some reason ford thought it might be a good idea for trucks.

Fuel Pump Issues

Reply #14 –
 is this really Crystal??? (been vacationing from the board myself here lately)

My 110 lph Carter pump died aftere only a year and a half. It warned me a couple times(no I didn't take the hints)then said "piss on you" 93mi from home... So yea I was very pissed off...

Testing the pressure really isn't going to tell you much on a interminent pump. Yea if the pressure is low you want to defiantly replace it, but if it runs OK I doubt it has a problem...

Finding interminents can be a pain in the ass but here's what I'd do.. Connect a small 12v lamp to the wires(the two on the passenger side, gage sender is on the driver side) leading to the pump back at the tank. Then run it into the car where you can see it. If it quits and there is no light when you first turn on the switch, or cranking you have a electrical issue elsewhere. IF the lamp comes on, your problem is in the tank...