301k '86 D21 dumping fuel thru intake system

[tstockma]

My old 86 Z24 just developed a new trick - running terribly, fills the air with gas fumes, and as I was on the way to work when it began, it also ran thru several gallons of gas for the last 20 miles I drove it.

I have already recently gone thru all vacuum hoses and they now look real good. Because I already had an EGR valve in hand, I replaced it - the temp valve on the EGR vacuum circuit is also good. No luck there.

I just turned over 301k miles and hate to think my old truck has breathed its last - the engine and 5-speed still appear stout - anyone have suggestions about throttle body or other basic parts in the fuel system? Thanks for your thoughts.

Tom in Parker Colo

[tstockma]

As I examine what's visible under the air cleaner, the Chilton's manual, and a few previous posts, I am beginning to think it's likely a stuck or bad injector. I haven't worked on injectors for this truck before, but if I have it right, instead of rails and an injector on each cylinder, this thing has 2 injectors in the throttle body under the long dome-like cover visible at the top?

My book says I need to pull the throttle body to work on them but I'm curious if it's possible to get at these things without pulling the body, since they're on top. (hmm, danger here - easy to drop screws and other material right down into the engine.)

I might try a cleaner in the fuel but this is dumping so much fuel I'll be surprised if that does much.

Thoughts? I am on the right track? Thanks all.

[tstockma]

Does anyone know, can I change out an injector without pulling the throttle body? And do these have 1 or 2 injectors? Thanks for any info.

[kibatheloanwolf]

Does anyone know, can I change out an injector without pulling the throttle body? And do these have 1 or 2 injectors? Thanks for any info.

As far as I know you cannot and they are dual injectors.

[tstockma]

Thanks very much. Drat that's all not exactly what I wanted to hear...but I need the info! I'll post results (it might be a week or 10 days).

[tstockma]

I have pretty much confirmed the issue is o-rings or the injectors themselves...took the throttle body unit and a rebuilding kit with gaskets & rings, to a rebuilder shop. They kept it overnight, and decided to not take on the project, saying the injectors were pretty stuck inside the unit, with brittle o-rings and old gunk making removal difficult and likely to break things. (They might simply be declining a nasty job, and I couldn't blame them for it...)

So my question - how difficult is it to get injectors out of the throttle body if old and gunked...300k miles old...can I find a small pipe or socket, and drive them out from the bottom?

Or does anyone have a good and not deathly expensive source for rebuilt throttle body assemblies?

Thanks for any ideas here...

Tom in Colorado

[osegundo]

You should download the FSM, it explains it there. Have you checked to see if your fuel pressure regulator is good?

[tstockma]

Great thoughts on both fuel pressure and the FSM - hunting the FSM down on this site, and scanning thru several hundred pages reveals you can drive it out from the bottom with a hollow tube - it even gives outside/inside diameters of the tube. (My truck is the '86, but the '88 FSM covers this first version of fuel injection.)

In case anyone else is reading this post and needs to do the same operation - drive the injector out from the bottom using a hollow tube, outside diameter 8mm, inside not less than 5.5mm - or .31 / .217 inches for us yanks.

Thanks and given the high miles on the truck, combined with the symptoms, I'm going to rebuild the throttle body myself without first checking fuel pressure (I'll check that when I reassemble). Might as well given how far I have it taken apart.

I'll update with results - it'll be a few weeks before I have a free weekend to do the deed.

[tstockma]

Praying a D21 guru sees this post!

(Sometimes life gets in the way of my plans. Just after last post, I put in new injectors...zero difference in the truck...life events intervened...22 months later, today I am finally back to working on the truck & pulled the front seat to access to ECM. With a jump, truck started within 3 seconds...)

Diagnostic code help needed! After starting, I got 12-13-23-24, all of which might be OK, and the truck sat & idled great. Air Flow Sensor / Engine Coolant Sensor / Idle Switch / Throttle Valve Switch.

After several minutes of idling & warming, much roughness suddenly started, and the smell of the exhaust reveals indeed something just happened to dump mass quantities of fuel down the injection system.

Diagnostic code 14 appeared (vehicle speed sensor, according to the reference I found). Why would vehicle speed cause a mass fuel dump into the system? That mass dump happens at all RPMs, all vehicle speeds, as soon as the engine partially warms.

All hints & thoughts appreciated. Should I be troubleshooting all sensors with codes (12-13-14-23-24)? Certain codes in that list which are likely to dump fuel into the system after partial engine warming?

[tstockma]

I am concluding that I don't know much about working with the ECU & that I've been asking stupid questions...so I'm going to treat each of the displayed codes as actual real problems to troubleshoot. Starting with engine coolant sensor (unfortunately, this is a new one from my last "round" 23 months ago, so there's more to the picture).