*Updated Again & Solved Again* No Start - No Power to Fuel Pump Relay (1 Viewer)

[bicycleagent003]

Hi Team,

I got stuck in Three Rivers, CA, this past weekend and had my truck towed to Visalia Toyota. The (master) tech there said there was no power to the fuel pump relay, and when he jumped power from the battery to the fuel pump relay it started and ran fine. He ultimately concluded the plug going into the ECU (which sends power to the fuel pump relay) was not connecting well and just pulled it out and reinserted it and they told me they started the truck, it was running fine, and to come pick up the truck.

When I went to start the truck, same problem. After resolving myself to wait for the tech to come back from lunch, I decided to put the key back in and try again. It started three times in a row (I shut it down a few times to test) and sounded fine, so I decided to drive home to Ventura and there it sits in my driveway. After I got home and shut it down I restarted it with no problem.

Other things to know:
- New Denso fuel pump and sock filter within the last 2 years
- New Toyota fuel filter within the last year
- Original fuel pump relay

A couple days before I took it to Toyota on a flat bed it wouldn't start and I checked the 15A EFI fuse, which is fine. At that time I also swapped around the spare EFI relay I have wih the one in the DS kick panel and the new one which is running in the EFI relay in the engine bay fuse box. That is, the truck wasn't starting and after experimenting with swapping the three EFI relays I have in various configurations in the 2 needed slots (engine fuse box and DS kick panel) the truck started fine and ran. I figured I had identified the bad relay by swapping. Then 2 days and 200 miles later it wouldn't start again.

Lastly, I am aware of the area below the ECU (behind the PS knee area speaker panel) where some owners have reported the wiring harness can rub against a metal tab and wear through the insulation, causing shorts. My harness sits off (not touching) the metal tab and per my examination the wiring harness appears never to have touched that metal tab. There are no wear marks at all even on the tape around the insulated wires.

Any thoughts, tip, suggestions would be greatly appreciated. Electrical stuff is not my strong suit so please explain your advice as simply as possible.

Thanks a lot,
Russell

*** Edited 12/8/16 after final solution found - I replaced the fusible link (described below), which initially seemed to have solved the problem. I actually kept a tally sheet on my dash with a pen and recorded 11 instances of successfully starting it after I replaced the fusible link. Then it wouldn't start again, and I went back through it with the multi-meter, bypassing the fuel pump relay, testing the fuel pump relay (FPR), etc. My conclusion then was that my FPR was intermittently failing, so I ordered a new one from Mr. T. After installing the new FPR it has now successfully started 50 times in a row (without a failure to start) over 6 weeks and I have declared the problem solved. Just thought I'd post this for others' benefit.
Intermittent problems are difficult and frustrating, and I'm not an electrical whiz. But I think I got this one licked.
Cheers.
*** Edited again 1/31/23 - The problem never recurred. It's been lots of miles and years, so I'm certain it was the fuel pump relay.

 

[lazy]

If you're sure that it is the fuel pump not getting juice, check the voltage at all 3 of the relays - EFI, COR (circuit opening relay) and fuel pump relay. If you find a place that doesn't have juice, you know where to start diagnosing.

Before doing that, I would drag a hot wire to the fuel pump and make sure it runs with a direct connection before you start going down the rabbit hole of chasing the electrical gremlins. Finally, check to make sure the plug under the driver's side passenger door and goes to the fuel pump is clean and has a good connection.

I can get you pin numbers to check voltage on, but I would start with making sure all connections are tight and that the fuel pump works.

 

[bicycleagent003]

Yes, with a hot wire to the fuel pump it works consistently. The Toyota tech did the same and actually offered to wire it up (wire from the battery to the fuel pump relay) just so I could get it home. If you could give me the pin numbers at which to check voltage at the 3 locations you mentioned that would be great. The idea is each of those should have 12V with the key in the On position, correct?

Thanks,
Russell

 

[lazy]

Yes, I would check and see if you have juice to the COR. It is in the driver's kick panel, on the cluster of relays all the way on the floor, bottom relay. Be sure to check both voltage wires so it can be determined if the relay is possibly bad, or if it is a problem with the feed (control) voltage or ground. It would be prudent to check if you're getting switched power to the COR. Below is a diagram I drew up for my GM swap, but as drawn is how it is setup with toyota.

Remove this piece to get to COR

Pic of COR (at bottom, the lone relay)

 

[jynx]

Fusable Link at Battery connection? Pretty sure in that diagram posted above, it would be in-line (lableled B-L switched power) from the (+) battery going to the relays that feed the fuel pump. The cluster attaches to the (+) terminal and then connects to the feed wires inside a couple of little plastic housings. If they go, you get no juice. I lost the one to the fuel pump on my 91, everything else on the truck worked but the fuel pump. jumper wire to the feed wire got me back to camp. I keep spares now.

Should look like this

 

[lazy]

Fusible links are easy enough to test.

I would not buy anything until you diagnose what the issue is....

It may be a good idea to start from the battery out. You can test fusible links, efi relay by checking for voltage on the efi wire (a plug with 3 ports, but only one wire), then e7 pin 22 which plugs into the ecm, then to the cor. You're just guessing and checking between fuel pump relay and battery, so start with the easier things... Fusible links and efi wire by the battery box.

 

[1973Guppie]

the only thing I will add is that there is a fuel pump connector under the rear drivers side wheel well that possibly might of come undone. This is the same connector that the FSM details to disconnect when changing the fuel filter.

 

[1973Guppie]

I read your description again and it sounds like an intermittent ground issue possibly? how does the efi relay ground? I would look closely at all grounds and connectors in the fuel pump system. I have seen even some small corroded pins cause intermittent power loss.

 

[bicycleagent003]

Hey Team,
Thanks for all the help. I spent some time with my EWD and FSM this weekend, and got a little more proficient with my multi-meter. It turns out I had a bad fusible link. It's nice to have the problem solved, but it's a bummer that I had a spare in my garage at home and I ended up paying a Toyota dealership not to solve or diagnose the problem. Stinks, but it's fixed now and I'm happy to have my reliable tank back in operation.
Thanks again for the assistance, guys.
-Russ

 

[cruiserdan]

Thank you for reporting back on the solution. Future sufferers will appreciate it.

 

[LS1FJ40]

Hey Team,
Thanks for all the help. I spent some time with my EWD and FSM this weekend, and got a little more proficient with my multi-meter. It turns out I had a bad fusible link. It's nice to have the problem solved, but it's a bummer that I had a spare in my garage at home and I ended up paying a Toyota dealership not to solve or diagnose the problem. Stinks, but it's fixed now and I'm happy to have my reliable tank back in operation.
Thanks again for the assistance, guys.
-Russ

I would venture that 99% of "electrical problems" I've had on any of my 80s have been linked to a bad fusible link or relay. I keep a spare of each in each 80. Cheap insurance.

I had my 92 towed in a fit of panic at 2am once because of a EFI Relay. Not knowing at the time that there are 3-4 of he same Relay in the truck I could've borrowed. And saved $250.

Glad you got it solved. It seems like a lot of these difficult "problems" end up being resolved fairly simply.

 

[1973Guppie]

weird + intermittent = fusible link

 

[Jgrauman]

Hi Team,


*** Edited 12/8/16 after final solution found - I replaced the fusible link (described below), which initially seemed to have solved the problem. I actually kept a tally sheet on my dash with a pen and recorded 11 instances of successfully starting it after I replaced the fusible link. Then it wouldn't start again, and I went back through it with the multi-meter, bypassing the fuel pump relay, testing the fuel pump relay (FPR), etc. My conclusion then was that my FPR was intermittently failing, so I ordered a new one from Mr. T. After installing the new FPR it has now successfully started 50 times in a row (without a failure to start) over 6 weeks and I have declared the problem solved. Just thought I'd post this for others' benefit.
Intermittent problems are difficult and frustrating, and I'm not an electrical whiz. But I think I got this one licked.
Cheers.

@bicycleagent003 did it ever cut off on you while driving as well? yesterday mine would start then die immediately. After a few attempts it started and ran fine. On the way to the store, it cut off while driving. Pulled over and same thing. had to start it a few times and it ran fine. Got to the store and it took 3 starts. Ran fine for a few miles then shut off again while driving home. I came home and could not replicate the starting issue, started just fine. I had it idle for a while and then just shut off. Started right back up again. Just drove down the street fine, with no issues. No CEL. I don't really have anywhere to start since it's so inconsistent. Found your post and thought it was a good place to start with the FPR.

 

[bicycleagent003]

Re the question just above, no mine would not die while running. If it started, it would keep running with no issues.

I guess FPR's can fail in different manners, and perhaps one of them would be fluttering internally, which would explain what you're experiencing. I have never heard of a relay failing like that, though, and it seems unlikely. With power to the FPR it should close the circuit and remain closed, thus powering the FP. It doesn't sound to me like your problem is a failing FPR, but that's just my two cents.

Good luck. I hate problems like these, mostly because they make me feel incompetent.

 

[baldilocks]

The relays that can temporarily paralize a 1fz are cheap. I replaced mine simply because they are from 2 decades ago and I have better things to do than waiste time figuring out why my cruiser won’t start or stay running especially when I really need it to run.

A circuit opening relay and FPR together are just under $100 on densoproducts.com

 

[bicycleagent003]

Yeah, I think the new baselining model should include items like relays and the fusible link because of the age of these vehicles and the fact that failure leads to being stranded.

 

[eaphelps]

Crank with no start SOLVED! I experienced the same problem as OP in my '96 Cruiser --- intermittent starting issues, cranks great and no ignition. Got stranded 2 times and had to call a tow. Getting spark and crank but no ignition. Guess is a fuel pump issue. Had the truck towed to the shop twice and it started no problem for the mechanic. He diagnosed a faulty crankshaft sensor and replaced. Drove it home and no start occured again intermittently. A few weeks later a relay inside driver's side kick panel started buzzing like crazy whenever key in the ignition along with no start. Buzzing turned out to be the Tail light relay in the driver's side kick panel relay bank - STRANGE. Swapped it out for the horn relay and same problem so the relay is fine. Also when the tail relay was removed, the buzzing moved up to the Head light relay in the fuse box in the engine compartment. Checked voltage to all of these relays as well as the EFI and COR and all getting 12V.

The relay buzzing made me think that the relay wasn't getting a stable current. Looking at the wiring diagrams for all of these relay circuits and the fuel pump, the common element is the fusible links. Went and removed the fusible links and they looked really nasty and corroded. Tested the continuity on my multimeter - one link showed 0.1 ohms, second showed 0.6 ohms, third 1.4 ohms. That high resistance could explain current problems. The connectors were really dirty and the clamps onto the wires themselves were corroded. Took some sandpaper and cleaned up the metal connectors and squeezed down the wire crimps on the connector really tightly with a pair of pliers. Now all three links reading 0.1 ohms. Hooked it all back up and relay buzzing cured plus great start on first crank! Ordered a new set of fusible links for $20 to replace. But if you are stranded and caught in a pinch, maybe can try cleaning up the fusible link connectors to the battery and will be able to drive home.