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Just bought an 89 4x4 pickup it had two cylinders misfirring the guy said the gas tank had some trash in it not rust but that the injecters were getting stopped up... so I replaced 1 and 2 injecters misfire quit drove it around for awhile and then lost number 1 cylinder again so my question is I saw where the guy had the fuel filter zip tied to the inner fender and its supposed to be mounted on the block would that let trash into the fuel rail?
Any help would be greatly appreciated btw I only paid 900 bucks for it 176xxx miles
The guy you bought the truck from is correct. It is not rust in the tank even though that is what it looks like. I would go thru the entire fuel system by what you are describing. The tank may have build up in it and you may want to clean or replace the tank depending on what it looks like.
I have seen the Return lines on these trucks clogged many times. A clogged Return Line really doesn't effect a truck on how it runs but seems to me that it just puts a lot of unnecessary pressure on the fuel pump.
Have you ran any fuel cleaner into the tank? I have seen that break up the build up and it will still get by the fuel filter and clog injectors. One reason I don't recommend running fuel cleaners in a tank unless you know the condition of your tank.
Another issue with injectors not firing is the Injector Harness has some poorly designed crimps. Two injectors share the same wire. The crimps in them corrode in some cases and will not fire an injector. The crimps will pass a resistance check but not allow enough voltage to fire the injector.
In each of my builds below, usually on the first few pages, I show things on the fuel tank and how I clean them if you want to check those out.
Here is what I have found for non firing fuel injectors. Probably not your computer being at fault, but the $3 Noid light will tell you if it is sending the signal. If it is sending the signal, check the crimps.
Check your fuel system and then to see if you are getting a signal to the injectors. To test the injector, you can use the little square battery (9 volt I think it is) a syringe filled with fuel injector cleaner with a rubber hose running to the top of the injector and some pressure. Power the injector with the battery for 1-2 seconds at a time and see if it sprays fuel.
Which injectors are failing? 1 and 3 or 2 and 4, that is how they operate in pairs. If the injectors are not clogged I suspect that the crimp is what is keeping them from not firing. Since the truck runs, and the other two are working, I don't think you have a fuel issue since the truck seems to be running.
To see if you are getting plenty of fuel to the fuel rail, pull the hose off of the back of the fuel rail and run it to a quart jar. With the Fuel Pump By pass jumper set, the key on, it should fill the jar in a minute or so. You will be able to tell if you are getting plenty of fuel that way.
Last edited by Terrys87; Mar 30, 2016 at 01:11 AM.
An fast injector check is to simply unplug it while the engine is running. If it runs the same, you know there is something wrong on that path and can isolate further with the above technique.
An fast injector check is to simply unplug it while the engine is running. If it runs the same, you know there is something wrong on that path and can isolate further with the above technique.
The guy you bought the truck from is correct. It is not rust in the tank even though that is what it looks like. I would go thru the entire fuel system by what you are describing. The tank may have build up in it and you may want to clean or replace the tank depending on what it looks like.
I have seen the Return lines on these trucks clogged many times. A clogged Return Line really doesn't effect a truck on how it runs but seems to me that it just puts a lot of unnecessary pressure on the fuel pump.
Have you ran any fuel cleaner into the tank? I have seen that break up the build up and it will still get by the fuel filter and clog injectors. One reason I don't recommend running fuel cleaners in a tank unless you know the condition of your tank.
Another issue with injectors not firing is the Injector Harness has some poorly designed crimps. Two injectors share the same wire. The crimps in them corrode in some cases and will not fire an injector. The crimps will pass a resistance check but not allow enough voltage to fire the injector.
In each of my builds below, usually on the first few pages, I show things on the fuel tank and how I clean them if you want to check those out.
Here is what I have found for non firing fuel injectors. Probably not your computer being at fault, but the $3 Noid light will tell you if it is sending the signal. If it is sending the signal, check the crimps.
Check your fuel system and then to see if you are getting a signal to the injectors. To test the injector, you can use the little square battery (9 volt I think it is) a syringe filled with fuel injector cleaner with a rubber hose running to the top of the injector and some pressure. Power the injector with the battery for 1-2 seconds at a time and see if it sprays fuel.
Which injectors are failing? 1 and 3 or 2 and 4, that is how they operate in pairs. If the injectors are not clogged I suspect that the crimp is what is keeping them from not firing. Since the truck runs, and the other two are working, I don't think you have a fuel issue since the truck seems to be running.
To see if you are getting plenty of fuel to the fuel rail, pull the hose off of the back of the fuel rail and run it to a quart jar. With the Fuel Pump By pass jumper set, the key on, it should fill the jar in a minute or so. You will be able to tell if you are getting plenty of fuel that way.
Awesome info thank you soo much I never knew you could use a 9v battery I also bought a gas tank I think that was my problem
Let us know what you find, the worst thing is when these threads don't have any resolution.
OK so I replaced the gas tank cleaned all the lines replaced the fuel pump and strainer fuel filter injectors did cap wires plugs rotar and I have went through the timing 3 times the misfire at idle is gone it idles like a champ but when u put a load on it (try to drive it) it starts missing again it's only around 2000 rpm then clears up idk I've done everything I know to do from the previous toyota I've had any suggestions? I'd like to put it on the road this week.
my '86 had the corroded crimp in the harness, it's very difficult to troubleshoot without actually cutting into the harness to assess the condition... my engine got weaker and weaker until it died on the freeway, barely running, i had to have it towed home.
i have no idea if your '90 had the same crimp done, i would look at the wiring diagram for your year of truck and see if shows the injectors being split in pairs, like terry described.
because the reason for the crimp was to hook both pairs together in the harness, looks like it was done by the factory after the fact... these are batch-fired injectors, they all fire at once, there was never any point in splitting the injectors into pairs, unless it was some weird driver design issue in the ecu.
we are talking worst-case scenario here, you could try swapping another engine harness in first, if you have one.
even if it passes the noid test, the corroded connection may still not be able to carry enough current to fire the injector.
Mar 26, 2016 | 07:13 PM
