87 GL EA82 wagon - new to me running problem

[DaveT]

Car has been great.  2 drives today, nothing unusual.  3rd run, I'm on the highway, going up a medium slope hill, 65MPH, 4000RPM, and start getting random pops / backfires / coughs / skipping.  Like seconds apart, not like 1 cylinder quitting.  Loosing power.  Lighter throttle lessens the problem.  End up downshifting to 2nd for a bit.  4000 RPM light load doesn't bother it.  Get off at the next exit, and continue on back roads.  Drove ok until the long hill, where again, same thing, random pops / coughs.  Downshift, get to the top of the hill - it's a good couple of miles or so.  Start down.  Idles to zero.  Crank, fire, shuts down.  As if the fuel pump isn't running, and you just dumped an ounce of fuel down the intake.  Coasted down the hill, a mile or so to a better place to take a look. 

 

Though maybe intermittent fuel pump, so swapped that fuse with another less important one.

 

Same thing, crank, fire, shutdown.  Hmmm.  Tried it again, while holding some gas, and it stayed running.  revved, stayed running.  Drove to work, since it's on the way home anyway.  Ran ok, until again, a uphill grade. 

 

Decided to head home, all back roads.  Started normal.  Ran normal until the hill up to my driveway, then same deal.

 

Normal temperature the entire time.

 

It's in my garage now.  

 

I've had water and crud in a fuel filter, this isn't like that, that just made power loss on the uphills, not the crazy pops / backfires bucking.  Not running like one cylinder dead, that's steadily rough, and low power.  Not like the time I had an IAC valve die, that just made idle = 0RPM, so I had to do it manually with the gas pedal.  Hard to imagine timing being a problem, because it comes and goes, except acts up on hills.  I had a catalytic converter block. almost totally once, that just made massive power loss, not the skipping / weird stuff I got today.

I'll put the fuel pressure gauge on it, see what that says.

 

Anyone else ever had this sort of thing?


 

[naru]

^{Plenty of times.}

^{Bad pump/filter sock.}

^{The pressure will drop off under high load going up a hill.}

^{Pump will not pass a flow test.}

^{Might pass a stationary pressure test(no load)}

Edited May 25, 2018 by naru

[Subaru Scott]

Sounds to me like secondary spark failure/grounding. 

 

Like a problem with the coil, maybe just oily dirt on top letting spark jump.

 

Could be the same issue on top of the distributor cap.

 

I have seen a few cases of holes burnt through the center of the rotor, but only on aftermarket cheapies.

 

just have a good look through all that, coil wire too. Swap things out if you have spares (I know you do).

[wagons]

Holding the throttle open and it started and stayed running? That right there gives me a hint that the throttle position sensor is bad. Starting with out it being open will fire but die. Starting with partial throttle now has a complete circuit. My old chevys are notorious for this, start with no throttle they fire and die. Start with trottle open, circuit is now open and ecu sees it and compensates fuel and timing. I may be way off but check the signal on the road or swap with one you know is good.

[subnz]

Agree also if not a fuel issue or not a blocked cat.

 

It could be a coil / distributor / leads etc issue.

 

If it runs ok when cold then gets progressively worse when up to running temperature and when under load (hills)

 

Look at coil (these can break down and fail under load and when warm also with intermitant random inconsistant misfires )

 

and also look at obvious stuff like rotor / distributor cap / and all 5 high tension leads - to spark plugs and coil to distributor

and low tension wiring / distributor module etc

 

High tension leads can break down under load causing misfiring getting worse under load and when warm / hot (like failing coils also), particularly if old or are of cheap replacement quality.

Edited May 25, 2018 by subnz

[somick]

The easy thing to check, like others mentioned, is a distributor cap and rotor.

 

Good luck,

Sam

[john in KY]

4000 rpm at 65mph?  Seems high to me. 

[DaveT]

4000RPM at 65 is very normal for the 3AT. From around 88 and up. My 86 had slightly different gears, and was a little lower RPM at 65. But even more gutless.

[Dee2]

Intermittent starting problems and intermittent running problems under load. 

 

I would suspect the fuel pump.  I would expect the problem to worsen over time with difficult/no starts and dying out even on level roads.  May be time for a replacement.  Certainly worth eliminating that as a variable.

[DaveT]

It's been a crazy few days... I will let everyone know what I find. Thank you for all of the suggestions.

[DaveT]

Some new data:

On my  93 the fuel pump is getting 12.5V while drawing 1.37Amps.   Does not change much at idle VS heavy throttle.  Drops to 1.35A

 

On the 1987 - Pump is getting 13V while drawing 1.26Amps.  Didn't get to try heavy throttle w/ high RPM, as my yard is too small, and I didn't care to risk getting stuck anywhere at the moment.

 

The fuel pressure is odd. however - instead of a steady 21PSI, I have the gauge bouncing between 20-22 PSI - steadily, at a pretty good rate that a mechanical gauge can keep up with.  Does not vary with throttle position.

[GeneralDisorder]

Is the vacuum signal to the fuel pressure regulator consistent? If you have uneven vacuum it may translate to uneven fuel pressure.

 

If so you should pinch off the return line. If you don't get a solid 50 psi then I would swap in a different pump. Easy enough to do for testing.

 

GD

Edited May 28, 2018 by GeneralDisorder

[DaveT]

Tests with engine running, room temperature, not run long enough to get to 190.

Pinched off return line gets me 45 PSI.

Current drawn by the pump rises noticeably while doing this, which does not surprise me.

Put a vacuum gauge on the small line to the pressure regulator, get no reading = no vacuum.

Manifold vacuum looked normal. 

Fuel pressure still doing the bouncing between 20-22 PSI

Still have to check the other things.

[markjs]

A bad MAF sensor can cause these EA82's to lose a lot of power, and you really notice it on hills, need to shift down to hold speed.

[YnotDIY]

still following this. working through similar issues on my 88.

Suspecting bad Fuel Pump. Let us know if you find anything else @DaveT

[DaveT]

Yes, I  will update.   Things have been a little nutty here.

[jono]

IF you were a nube I would suggest the new to you needs a decent replace all replaceable type service first then come back. I ask how many customers got the pcv valve replaced every 24 months as suggested in service manuals when these cars were new? How is yours and its whole breather set up? Choked with carbon?

 

When fuel is low also worth removing sender for peak a boo inside tank

[DaveT]

Update:  The spark plug wires all look ok.  Not brand new, but not ancient.  NGK.  Cap and rotor look ok, nothing unusual there.

As a test, I took a spare wire and plug, and connected that to one of the distributor outputs, and let the plug body contact the wire to the plug of that cylinder.   I only ran this at idle, but the spark could jump a good solid 1/2" and not even bother the engine running.

I have a pressure gauge T'ed into the inlet side of the throttle body.  Amp and voltmeters wired to the fuel pump feed.  So I can monitor these when I actually risk going out and getting stuck on a hill....

Letting one of my spare fuel pumps soak with fresh gas inside it - they are stuck and won't spin.  NAPA lists a replacement that looks identical, but they are out of stock can't back order, and pricey.  I remember someone mentioning a low cost fuel pump for some other car that works, but not what it was.

Also remembered that I had installed a tap on the fuel system on this car so I can plug my generator into it to use the car as a fuel source.  So I can use that port as a test to verify the fuel tank is not clogged.  I used boating quick connect fuel connectors.

[DaveT]

So far, the stuck pump is still stuck.  Ordered a carter P5000 and a strainer.

[Subaru Scott]

I was gonna say the Ford F150 used an inline pump, but that Carter looks like a nice unit!

Yeah, I had several early Legacy pumps, and an EA82T pump stored away. They do not like to dry out...

Even soaked one in ATF for a couple months and still stuck. 

[YnotDIY]

11 hours ago, DaveT said:

So far, the stuck pump is still stuck.  Ordered a carter P5000 and a strainer.

Ordered my pump as well. Should be testing it out soon.

excited to hear if this fixes your issue.

[DaveT]

While waiting for the pump, I got a chance to test the flow from the tank via my generator port.  Seems fine, fuel gravity flowed at a rate that seemed normal for the line, and not blocked pickup.  The port is T'ed in before the stock pump.

[DaveT]

I got the fuel pump today, wow it's nice.  All brass.

[robm2]

For the price of it, a new HT lead from the coil to the distributor would be worth a try, if your new pump dosen't help.

[Silas Cruse]

Which pump , part number did you go with ?