87 R10 TBI injectors will not spray

[Cuba]

Wow!! Excellent job! It takes so much patience sometimes to tackle diagnosis... I find it tougher with our own vehicles than a customer's or friend's one.

So that one injector not firing? You think it's the injector itself? In my whole time working on TBIs, I've never had them fail... but stranger things have happened. Maybe comparing the resistance with the other, although, that's not a fullproof way to tell if it's dead.
Or does the noid light up on the dead injector plug?

 

[Honky Kong jr]

Checking the resistance of each injector will give you a good indication of the coils condition for sure.

 

[IROCmenace]

Yeah either the injector is dead or gummed up enough the ECM cannot open it. I have opened it with direct voltage from the battery recently though but maybe I killed it. Last night I swapped the plugs to the opposite injector to make sure it is not the plug itself. Still wouldn't open but the good one does with either plug.

When I ohmed it last night I got nothing but I was in a hurry, may try again.

Even more wierd is that I noticed a small spark jumping from the throttle body to the collar that goes around the injectors. I had it lifted up to see the inhector spray and could see a small spark jumping from the top of the TB to the collar. I am just guessing but I assume it is because the injector is shorted.

 

[IROCmenace]

Wow!! Excellent job! It takes so much patience sometimes to tackle diagnosis... I find it tougher with our own vehicles than a customer's or friend's one.

So that one injector not firing? You think it's the injector itself? In my whole time working on TBIs, I've never had them fail... but stranger things have happened. Maybe comparing the resistance with the other, although, that's not a fullproof way to tell if it's dead.
Or does the noid light up on the dead injector plug?

Thanks, the noid light did light on that plug. And I swapped plugs to check wiring. I am going to hit the u pull and get a few and swap them out.

 

[Cuba]

Thanks, the noid light did light on that plug. And I swapped plugs to check wiring. I am going to hit the u pull and get a few and swap them out.

Just be sure to get the same size engine or bigger TBI injector... they differ in sizes (output) & obviously you don't want less output or spray than you had originally

 

[rt66paul]

Have you checked fuel supply and pressure? A sitting truck can have all types of problem with fuel and load up the filter. The sock over the pickup tube could be compromised. Allowing the pump to pressure up may allow for spray, but not continus spray.

 

[Jims86]

Replace that injector with the EXACT size...do not go bigger.

 

[IROCmenace]

Have you checked fuel supply and pressure? A sitting truck can have all types of problem with fuel and load up the filter. The sock over the pickup tube could be compromised. Allowing the pump to pressure up may allow for spray, but not continus spray.

Thanks for the reply. I got it running though.

 

[Jims86]

Guys, one more thing to check when problems like this occur, is the small rubber hose between the fuel pump, and tank outlet tube. Over time, these will develop a hole, and is the worst thing to diagnose. It's one of those "outta site, outta mind" things that will leave you with a lot less than a head full of hair.