and, another fuel pump dies. limped it home this afternoon, gauge indicated only about 15 to 17 psi, couldn't increase pressure by pinching the return line.

20 minutes later, pump # 9 is in. pressure @ 32 (42 without the vacuum line). still have one more pump on hand when this one goes. then, i'm going to try one of the pumps from my 95 subaru and see if i can get one of them to work with the 4runner.

wally

 

you sure it's not the FPR that's acting up? If FPR is bad, even if there is enough fuel pressure before it, it may not respond to vacuum port at atmospheric pressure and therefore not increase output fuel pressure - which is what our FP gage is monitoring.

 

well, pinching the return line should give some indication, and the pressure did not rise at all from 15-17 psi. pressure shot up to 42 psi with the new pump and same FPR, and dropped to 32 after attaching the vacuum line. pressure shot to about 50 psi when pinching the return line w/the new pump.

i wish it was the FPR. that's easier to change than the pump.

 

It is hard to imagine that you've gone through so many pumps. Is it possible the pump motor is getting a low voltage condition as you drive?

That's the only thing I can think of that would be burning out the motors. (Admittedly, my electric motor knowledge is limited.)

DCMatt

 

I bought a new $12 fuel pump off of ebay around 8 months ago, it has been working flawlessly. When I inspected it out of the box I could see it looked like someone had lightly ground the side with an angle grinder, and in the grind mark i could see the Airtex logo and part number not sure what kind of back door operation they were running but I guess I got a good deal.

 

the bumper on my 1995 toyota pickup needs a new bumper. The only one i can find is one for a 1995 toyota tacoma. Will the tacoma one work on my pickup?

 

Will a Tacoma bumper fix a "Hard start w/ low idle until revved, hot or cold" issue?

 

I'm also beginning to think that way. It's pretty unpredictable how inductive loads like a motor would react to the wrong voltage or fluctuating voltage.
An inductor (coil) like the windings of a motor wants to see a constant voltage across it. If that voltage is suddenly disconnected or fluctuates, the coil will generate a current to try to keep the voltage the same. That may very well affect other parts of the motor, like arcing across the brushes or slip rings (Sorry, I do not know which one the fuel pump has).

Wally,
May I suggest you double check that your fuel pump to C.O.R. circuit is all good?

 

thanks ray, i'm going to do some voltage/resistance testing of the pump circuit. i've parked the runner for now until i can run the tests, and am instead driving my '89 camry. that's a 12 mpg boost.

wally

 

Cool. Tell that to Redeth. Your improvement of 12MPG is his 3.0 4Runner's MPG. Poor Dude.

 

ran some resistance/voltage checks on the fuel pump circuit.

resistance is 1.7 to 2.1 oms. same at the pump connector at the tank, and the connector shows 12 volts when the pump is running. no spikes/drops. a steady 12 volts. of course, it's stationary in the driveway.

wally

 

update.

still running the pump that was installed around 2-10-2016. two whole months. still getting correct pressure.

i did have another leaking injector, so i removed the plenum/rail/injectors (again). also changed the fuel filter (4th in less than 50K miles, just because i've had this apart so many times). cleaned the injector screens, and reinstalled using a drill press. all new grommets/o-rings, but reused the spacers. new crush washers for fuel fittings (damper & filter).

used injector cleaner and compressed air to blow out the pressure line from the filter inlet fitting back to the tank (disconnected), as well as the vapor return line and FPR return line. the FPR return line had a bit of obstruction in it, but is now cleared.

there was bit of metal filings in the rail and fuel line. i surmise that this might be from the first pump that quit, back in 2013. perhaps the filter didn't trap all of the filings, allowing it to get both to the injectors, clogging the inlet screens, as wall as backflow/wash to the fuel pumps (multiple, since i've got #9 on there right now).


every time i replaced the pumps, i replaced the fuel pump "sock" pre-filter, and 1/2 the time replaced the fuel filter. hope this has solved some of the fuel pump issue.

also tested voltage, etc, and was unable to find any high load areas or voltage spikes/drops. pretty much tested in spec.







been here a few times, inside of plenum is pretty clean, minor carbon





removing the rail & injectors





part of previous injector rewiring visible





using drill press to install screen filter in injector





close up of upgraded injector connector. much better than the factory piece of crap.





everything but the plenum back on, with new grommets/gaskets, etc. new injector connectors are visible. these can be unplugged with the plenum and everything else in place, if wanting to test for a misfiring injector, and will also allow swapping the connector to a different injector to help diagnose a non-firing injector, also with everything in place - no more trying to unclip the piece of ˟˟˟˟ factory connector with no space available to get a small pick/screwdriver to release the wire clip


wally

 

So hard starts and rough idle came back. Sometimes at full stop, I could hear the C.O.R. clicking, meaning the AFM flap is not getting enough air to open it and to keep COR coil energized. Idle at AC on temporarily fixed problem. I do not have a tachometer, yet, so I did not mess with the idle. Fuel pressure is good.
I found my air filter pretty dirty so I replaced it. Hard starts and rough idle when cold still happened, although less frequently.
Finally, I got CRC throttle body cleaner, cleaned the TB flap and where it contacts the TB bore. I was not to dirty but there were some stains on above parts. 2 days after cleaning the TB and I have not had any hard starts and idle seems smoother.
Could it be possible that TB flap sticking could cause the hard start and rough idle?

We're having a heat wave in So Cal so I'm not sure if warmer nights help mask the real problem. I'll monitor and report back.

I'm noW shopping for a tachometer. Thought about getting a dash mounted one but leaning more toward a more precise handheld/diagnostic one. Do you have a recommended tachometer - timing light combo tool? Would appreciate any tips.

 

the AFM flap sticking can lead to the stuttering idle. i've experienced it with my '89 camry. the sticking flap never caused hard starts, though, just poor idle/stalling when coming to a stop.

i "solved" it by pounding it (the AFM) with my fist while idling. lol. i suspect that the car sat for a bit prior to me buying it. once it started getting regular use, the AFM flap sticking and stalling have disappeared.


on a positive for me, i'm still on my 9th fuel pump (knock on wood) that has been installed for several months and a few thousand miles, holding a solid 28 to 40 psi as needed.

wally

 

Thanks, Wally. I only did the throttle body. Didn't do AFM, yet because I find AFM a little more sensitive. May do it later if and when idle hard start issue come back.

 

Hi guys,
I cleaned all my temp sensors and the threads on the coolant bypass/intake manifold. As soon as I put everything back together and topped off the coolant, truck went Ta-Da-VROOM!

Details follow:
Well... hard cold starts persisted. After more research I realized that:
1) The CSI timer switch (brown connector) gets its ground from contact of its brass body with the manifold metal. Meaning, the threads on the manifold metal and the CSITW should be bare shiny metal.
2) The ECU temp sender (green connector) must affect starting and cold idle, and finally
3) The BVSV (Bi-metallic/temp-sensitive Vacuum Switching Valve) located on the lower manifold above the CSI Timer Switch and the ECU temp sender, probably also affects cold start and idle. (There has been minimal or no attention to this on discussions about cold-starting.)

So when I flushed my cooling system (and replaced my thermostat with the 2-stage one), I cleaned all the above sensors, and threads where they screw into.

Thirty years worth of scale on BVSV:


Scaled CSITS and ECU temp-sender (CSITS was cleaned earlier to help fix hard starts but I overlooked the threads on the manifold.):


Scaled temp gage sender:


Sensors Cleaned:


Scaled thread on coolant bypass manifold for CSI timer switch :

THIS IS A MUCH-IGNORED DETAIL THAT IS CRITICAL TO PROPERLY GROUNDING THE CSITS.

Here's why:



AND... I did all these in the rain - LOL!

 

pump number nine is still working, nearly a year later. i wish there was a specific thing that apparently solved going through fuel pumps, but there isn't. unless it was the metal filings residue, for which i do not know the source.

wally

 

Any luck in ever figuring out the overall issue? This thread is a few years old and maybe dead, but my 87 is having some similar issues and I am looking for any updates that may be available?

 

directed at the OP? or one of us "thread hijackers"?

 

Wally -

Thanks for the reply when I first replied to the post I didn't realize it was 8 pages long, but really I am reaching out to anyone on this thread with any thoughts on the matter. Also, today when my 4Runner died on me at the gas station I ran into another guy with an 88 4Runner. He mentioned to me that he had an issue once in his where he swore up and down that it was the fuel pump or something similar but it turned out to be the "Circuit Open Relay" located near the ECU by the front speaker kind of.

My 4Runner today when it died though it would turn over, run for maybe a second and then when I would hit the gas pedal it would stall out, I tried to crank it over again after that and it turned over and then sputtered out right away. Over about the past week, I noticed it bogging out on me less than a handful of times and it would always correct itself after I gave it some gas. But today is when it died out on me all together and then would fire and just sputter out. Prior to the past week, however, the truck had not been driven very frequently and had sat for a few weeks to a month without any action.

My truck just had the top end rebuilt within the last 1500 miles, has all new ignition system cap, rotors, wires etc