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1988 Pathy TBI issue


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Hello, All. I'm new on here. My name is Dennis. My 1988 Pathy is the first Nissan I've owned.

I really need help. I have a 1988 Pathfinder that was in limp mode and I retrieved a bad injector code. I replaced BOTH injectors and now she don't start. I can pour a little fuel down the throttle body and truck will run until that fuel is gone. PLEASE HELP.

 

 

THX, Dennis.

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Clearly the injectors aren't putting fuel in. The likelihood of two new injectors being DOA is fairly low, so let's rule them out for the moment. Any chance you removed the fuel pump fuse to run the pressure out of the fuel system before doing the injector swap and forgot to put it back in?

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^Good question!

 

Do you get any codes now? Anything different?

Were the connectors in good condition?

Have you tried moving the wires around near the connectors to see if there is anything seperated?

 

I'm going to move this to the 1986.5-1989 section as that is the years with the TBI...

 

B

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  • 4 weeks later...

check your fuel filter also if its clogged it wont put fuel out. Remove your the filer and put the line in a water battle and turn the key. If you have fuel then it could be in the injectors or in the line from filter to injectors. take your injectors back out and reinstall them and hook up the fuel filter and try to start it again. still if nothing then your problem is in the injector line somewhere. try to clean it out or replace them. if the injector lines are bad them you might have stuff in the gas tank that's making you have this problem. that's what I have to do on my 87 pathy before hope it helps

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Clearly the injectors aren't putting fuel in. The likelihood of two new injectors being DOA is fairly low, so let's rule them out for the moment. Any chance you removed the fuel pump fuse to run the pressure out of the fuel system before doing the injector swap and forgot to put it back in?

 

 

^Good question!

 

Do you get any codes now? Anything different?

Were the connectors in good condition?

Have you tried moving the wires around near the connectors to see if there is anything seperated?

 

I'm going to move this to the 1986.5-1989 section as that is the years with the TBI...

 

B

 

 

check your fuel filter also if its clogged it wont put fuel out. Remove your the filer and put the line in a water battle and turn the key. If you have fuel then it could be in the injectors or in the line from filter to injectors. take your injectors back out and reinstall them and hook up the fuel filter and try to start it again. still if nothing then your problem is in the injector line somewhere. try to clean it out or replace them. if the injector lines are bad them you might have stuff in the gas tank that's making you have this problem. that's what I have to do on my 87 pathy before hope it helps

Thanks to the 3 of you who took the time to respond to my post and my sincerest apologies for taking so long to respond.

As for your questions: fuel pump fuse was NOT removed, fuel pressure out of filter is 37lbs. As for the connectors, I removed the injector wires from one connector and plugged them directly into the other connector. Didn't help. No codes showing at this time. If I didn't shave my head I'd be pulling my hair out.

Thanks again for all the help. Any more ideas would be appreciated so long as you don't recommend a grenade (like my wife).

 

Dennis

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Hmm. Do you have a multimeter? Either your new injectors are both DOA or there's a problem with the wiring. Here's a partial wiring diagram of the injectors from EF&EC-120 of the '89 service manual. http://www.nicoclub.com/FSM/hardbody/d21_truck_1989.pdf

Screenshot2014-11-06at112835PM_zps4b5b3c

 

It looks like both injectors share a white wire with a red stripe, which goes to the computer and to battery +. If that wire broke while you were swapping injectors, it would take both injectors offline.

 

I am a little puzzled by the safety relay, but near as I can tell, it's designed to disconnect the injector circuit from battery + if the alternator overcharges the battery, probably to protect the ECU and the injectors. (The diode on the coil is reverse-biased, so current can't flow through the coil and open the contacts until the battery voltage hits the diode's breakdown voltage and overwhelms it.) This isn't spelled out in the manual anywhere I've found, and I'm not an electrical engineer, so I could be wrong on this.

 

Anyway, I would expect to see battery voltage between ground and the white/red stripe wire in the injector harness. If it's not there, I'd check the fuse links and try to track down that safety relay to make sure it hasn't burned out or something. If it doesn't show up in the "location of electrical units" pages, the plug number should correspond to the wiring harness diagrams in the EL section. If the white/red stripe wire is powered up, then the problem is probably in one of the other two injector wires (the solid black and black/blue stripe, and yes, blue is "L" on Nissan diagrams for some reason). You can also test the injectors with an ohmmeter to make sure they're alright.

 

The EF&EC section of the FSM has a series of troubleshooting checks which are probably better than mine. I haven't read through it all, but I haven't seen it recommend grenades yet, which is promising.

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  • 4 months later...

Slartibartfast, thx for the diagram. I have no voltage to the white/red wire at the connector. Also, I have no voltage coming out of the ECCS on white/red wire. Any more pearls of wisdom? Time to change the ECCS?

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Hi Dennis, im new to the forum,

Slartibartfast showed a wiring diagram

The w/r wire that shows starting form the battery, next goes to a fuse, then to a safety swith/relay, then to the injectors, and terminates at the e.c.c.s. . I would start by testing voltage from the beginig at both sides of the fuse working yourway to the safty swith. test the safty switch for both a positve curent and also for a ground by using an ohm meter. Chances are if there is no voltage after the safty swith then its bad. By the diagram everything else gets voltage before your e.c.c.s does, so changing it out wont fix it. If you have voltage to the safety switch and not after try making a temperary jumper wire to bypass it. Remember the word temperary!!! I hope this help explain it a little more.

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