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What is it about the 80's 4Runner fuel pump? They all decided to fail at the same time. Mine died too a while back and I have not replaced it. I'm looking forward to cooler weather to fix it. I have the Denso pump, video by Alexman, and a new aftermarket hanger from eBay. I'm kind of nervous because I'm no mechanic. The dog is worried.
changing the pump in these is straightforward. i changed two on the side of the road, back when i went through 7 or 8 pumps in a one year span, with no clear resolution on why they failed. there’s a thread here on yotatech somewhere about it (here it is...middle of thread, my fuel pump failures). the one running right now was installed in early 2016...also a bit about it on my maintenance thread on t4r.org
Last edited by wallytoo; Sep 18, 2022 at 12:48 PM.
What is it about the 80's 4Runner fuel pump? They all decided to fail at the same time. Mine died too a while back and I have not replaced it. I'm looking forward to cooler weather to fix it. I have the Denso pump, video by Alexman, and a new aftermarket hanger from eBay. I'm kind of nervous because I'm no mechanic. The dog is worried.
my only concern was the screws that hold the top on but I didn't realize that they were hex head. I went and got the vessel bits to hook to my impact driver and of course lost them when it was time to do it. Oh and then I wondered if I would break the fuel line that attaches to the flexible fuel line so I actually got another hanger for the fuel pump and turns out it's the wrong one for the smaller tank.
changing the pump in these is straightforward. i changed two on the side of the road, back when i went through 7 or 8 pumps in a one year span, with no clear resolution on why they failed. there’s a thread here on yotatech somewhere about it (here it is...middle of thread, my fuel pump failures). the one running right now was installed in early 2016...also a bit about it on my maintenance thread on t4r.org
how did you determine that it was the fuel pump? I'm a terrible roadside mechanic unless it's something that I already knew was an issue before it let go. I just did this as kind of a preventive maintenance procedure since the thing was 35 plus years old. And I kept the old one.
how did you determine that it was the fuel pump? I'm a terrible roadside mechanic unless it's something that I already knew was an issue before it let go. I just did this as kind of a preventive maintenance procedure since the thing was 35 plus years old. And I kept the old one.
did you read that thread? i added a fuel pressure gauge, and when it shows less than 28 psi, with the FPR return pinched, i know the pump is not working at full capacity.
of course, no fuel at all via the return, with the key on/engine off/Fp to B+ jumped, also shows this, unless the injectors have massive leaks.
plus, as noted, i went through more than 7 pumps in just over a year. i got pretty familiar with diagnosing the pump not pumping.
Last edited by wallytoo; Sep 18, 2022 at 03:29 PM.
did you read that thread? i added a fuel pressure gauge, and when it shows less than 28 psi, with the FPR return pinched, i know the pump is not working at full capacity.
of course, no fuel at all via the return, with the key on/engine off/Fp to B+ jumped, also shows this, unless the injectors have massive leaks.
plus, as noted, i went through more than 7 pumps in just over a year. i got pretty familiar with diagnosing the pump not pumping.
did you read that thread? i added a fuel pressure gauge, and when it shows less than 28 psi, with the FPR return pinched, i know the pump is not working at full capacity.
of course, no fuel at all via the return, with the key on/engine off/Fp to B+ jumped, also shows this, unless the injectors have massive leaks.
plus, as noted, i went through more than 7 pumps in just over a year. i got pretty familiar with diagnosing the pump not pumping.
alright now I've read the thread, I didn't see the link originally. I no longer own a computer so reading all this on a phone. All them fuel pumps and no reason for a failure. That's disappointing. Maybe I should have read that thread before doing mine. I did it as a PM type of thing because the old one is probably original.
yeah, i added the link once i was on my computer (rather than my tablet). it was a pain to constantly pull the efi system apart, but i got pretty good at it and knew exactly which sockets/tools were needed and where. the upshot is that i'm willing to dive in and take the stuff apart; nothing in there that anyone with a tiny bit of patience, an FSM, and normal tool set can't take on. i will say that once i added the pressure gauge, diagnosing the fuel delivery got a lot more instantaneous!
the PM stuff i'd tackle would be vacuum hoses, coolant hoses, wiring improvements - instead of replacing functioning "parts" like COR, fuel pump, afm, tps, etc. as an example, my '95 legacy wagon, which my first 4runner replaced in 2013, had 300k miles on it, and was still running its two original fuel pumps. the car was plenty rusty by then, but those pumps were fine - as i understand it, the guy i gave it to still drives it in his sandpit, and let his kids learn to drive stick with it (in the sandpit).
Last edited by wallytoo; Sep 19, 2022 at 04:05 AM.
What is it about the 80's 4Runner fuel pump? They all decided to fail at the same time. Mine died too a while back and I have not replaced it. I'm looking forward to cooler weather to fix it. I have the Denso pump, video by Alexman, and a new aftermarket hanger from eBay. I'm kind of nervous because I'm no mechanic. The dog is worried.
I am the AlexMan. Depending on what part of Virginia you're in, I can lend a hand.
just an FYI/update for this super old (helpful) post, my 86 RTE doesn't have an STJ to the ECU (this is correct in the FSM but I was confused for a long time)
I rehabbed my wiring harness during my rebuild - I started off just planning to add in the starter relay, but ended up tearing out a lot of the old aged wiring and replacing it. While a lot of the ~86 wiring harness connectors are unavailable/hard to find, the injectors all use a standard GM "EV1" connector, including the cold start injector and (amazingly) the Injector Time Switch too, so I grabbed 6 (4x fuel injectors, 1x cold start injector, 1x cold start time switch) of them from my local NAPA ran all new wiring for all those circuits.
I used https://www.napaonline.com/en/p/CRB218457 - which were the more expensive option but are much easier to remove than the cheaper ones and have nice rubber grommets.
Still looking for a source for the other square connectors...
Amazing scenery! ... Hey back to the 4runner, did you ever do the fuel pump swap? I just did on my 85 . Not a bad job. I got the idea from you.
Originally Posted by Damion812
how did you determine that it was the fuel pump? I'm a terrible roadside mechanic unless it's something that I already knew was an issue before it let go. I just did this as kind of a preventive maintenance procedure since the thing was 35 plus years old. And I kept the old one.
Originally Posted by Nervo19
What is it about the 80's 4Runner fuel pump? They all decided to fail at the same time. Mine died too a while back
Mine was sort of corrective maintenance because I was starting to get worse long-cranks before combustion issue. Then when I finally replaced it @289,276 miles, I found the pre-filter screen torn, and the resistance of pump, although not mentioned on the FSM is much lower than the new pump. So I'm guessing, 200,000 miles would be a good time to buy spare pump AND inspect the old one, OR better yet if there is any slight issue with fuel system the suspect, replace the old pump and keep it as spare.
Originally Posted by wallytoo
...no clear resolution on why they failed. ...
@wallytoo , Assuming good fuel and good quality OEM pumps, the only thing I can think of is if there is some power loss (voltage drop) on your wiring to the pump such that it is not getting proper voltage. Unfortunately, I haven't had chance to monitor normal voltage at pump.
Originally Posted by arlindsay1992
I am the AlexMan. Depending on what part of Virginia you're in, I can lend a hand.
Thanks for sharing your knowledge and experience, @arlindsay1992! It gives us more confidence to do things ourselves - which is the best way to do things.
Last edited by RAD4Runner; Sep 28, 2022 at 11:51 PM.
just an FYI/update for this super old (helpful) post, my 86 RTE doesn't have an STJ to the ECU (this is correct in the FSM but I was confused for a long time)
I rehabbed my wiring harness during my rebuild ..
Good job on wiring rehab! A lot of issues are not from bad components but from bad wiring / connections.
RE: No STJ to ECU on the 1986, that is correct. I haven't seen the 1987 schematic but I know the 1988 has STJ to ECU. I discussed it here, too: https://www.yotatech.com/forums/f116.../#post52385373
Last edited by RAD4Runner; Sep 29, 2022 at 12:03 AM.
Alexman, I'm in the RVA area. The '89 is not really a priority. I have all the parts, the tools assembled, and your excellent video ready when the weather is perfect and I'm in the mood to work on it. My son just came down with the bug today, tested positive, so I guess I'm doomed for the next ten days or so. LOL. My younger son used to daily drive it, but he's moved to western VA. I've belonged to Yotatech so long my 9-year-old is 23. I bet it only takes about an hour to complete.
Sep 1, 2022 | 11:57 AM
