4.3L w/ 16196395 Fires but will not run

[DanK]

First let me say that I don't have a clue what I am doing...or, rather, didn't until I found this forum. So now I'm a partially informed idiot. I probably wouldn't have attempted my engine swap without it. I know your focus is FI swaps so this should be easy.

Here's what I've got: 1982 J**p Scrambler swapped Iron Duke 4-cyl for a 4.3L TBI (vin Z) from a '93 Astro van. Complete overhaul bored 30 over...did it myself so that could be part of myproblem. PCM is 16196395 BJLA. T-18 4-speed, cheap e-bay VSS. Retained all other factory sensors. No exhaust system yet.

After messing around for a while with TDC and distributor placement I got it to run. Sounded good, smooth idle. Only thing was, after revving the engine, it would slowly wander back to idle. It would start right up on half a crank. Drove it up and down my 1/4 mile driveway a few times. The last time it started sputtering and I had to feather the throttle to keep it running. Back at the garage I let it die and now will not start. It fires but will not run. I do have to put the throttle to the floor to get it to fire.

PCM threw some codes but all are associated with the automatic transmission which, of course, I do not have. Key-on voltage checks are all good except "B13" MAP signal. It should be 4.9V according to the FSM, I am getting 3.39V. I am at 8500 ft. elevation so maybe thats OK? Just replaced the fuel sending unit because the gauge didn't work and the pick-up sock looked a little clogged (it was). Fuel pressure at the TB is 9-10 lbs while cranking.

Somebody please point me in the right direction.

[Bill usn-1]

9-10psi is a little low on the fuel pressure but it should still run if it doesn't go any lower.
keep the gauge on it.
are you running a fuel filter before the pump?
have you replaced it?
what is the pressure when you get it to fire?

next is timing.
what is the timing with the bypass open and cranking the engine?
is it steady or jumping around?

Are you running a power relay or are you tied straight to the truck wiring?

[DanK]

Thanks, Bill.

I agree the pressure is marginal. I am using the E2000 pump w/ the clear plastic (G3?) filter in front of it. I have not changed it but will. I think the pressure stays at 9-10 when it fires but I'll pay closer attention next try.

As for timing, I did it "by ear". I'll get a light and throw it on.

Power is through a relay per your excellent FAQ instructions.

Bill - I really appreciate your assitance. Please bear with me as we work through this as I have 4 school age offspring with all the associated obligations. If you don't hear from me for a few days it is only because I am otherwise pre-occupied. I will sse this through and share the results.

Dan

[DanK]

OK, replaced the G3 filter and the spark plugs (they were black and damp). Same result.

Disconnected the set timing connector and it started right up. As for timing, I can only get it to about 8 degrees BTDC before the distributor cap hits the linear EGR. Do I need to pull the distributor and set it back a tooth or two? It needs to be at 0 degrees, right?

Thanks for the help.

[Bill usn-1]

Yo should start from scratch and pull the #1 plug and set the engine at TDC on the compression stroke.
If you are not sure how then you need to get someone to help.
with the plug out put your finger or thumb over the hole.
Have someone "bump" the switch so you just barely turn the engine.
do this until you feel the pressure pushing your finger off the hole.
Then look at the timing mark. It should be getting close to 0.
I recommend turning the engine by hand till the mark lines up.
Then pull the cap and make sure the points line up on the pickup and the rotor is pointing at #1 post on the cap.

If you can't get them lined up then pull the distr and reset a tooth or 2 to get it lined up.

Also if you think it is flooding during cranking...which it shouldn't if everything is right...just hold the pedal to the floor while cranking just like a carb engine.

[DanK]

Ended up having to reset the distributor a couple of teeth. Got it set to 0 degrees with the set timing connector disconnected. Reconnected, timing sits at about 10-12 degrees at idle. Fuel pressure is constant 9 psi. Seems to run very well.

However, after revving, it doesn't return to idle promptly. I don't have a tach so I'm guessing here, it slowly drops to about 1500 rpm, sits there for about 5 or 6 seconds then drops to a "good" idle, about 5-600 rpm. Does it sitting still and driving. Throttle cable doesn't seem to be binding. Butterfly valve closes completely. The only codes are associated with automatic transmission.

Any suggestions?

[Bill usn-1]

Sounds like the IAC is reacting to the throttle follower tables.
You can drive the IAC closed by connecting pin A and B of the aldl plug and then turning the key on.
The IAC should buzz.
Then just unplug it.

TRurn the key off and disconnect jumper.
Then start the engine and see how it reacts without the IAC.

This would also be a good time to set the idle per the initial setup procedures.

Or leave it disconnected and see how it does.

Do you have the pk/n wires connected or open?

[DanK]

Thanks, Bill. I'll give that a try. If it behaves well w/ the IAC unplugged does that necessarily mean it is bad?

As I recall, I left the pk/n wires open. I think I just clipped them 6 or 8 inches from the PCM. I'll check it out.

[DanK]

I had a few minutes last night to disconnect the IAC per your instructions. Upon re-starting w/ the IAC unplugged the idle was pretty high - I'm guessing 1200-1500 rpm and very steady. Guess I really need to get a tach. After revving it would settle quickly into that range. Also noticed that the fuel pressure was steady at 9.5 psi up from 9. I didn't have time to let it get to operating temperature so I am not sure if you can draw any meaningful conclusions.

Should I go ahead and set the idle per the initial start-up procedures? I was operating under the assumption that I wouldn't need to do that since the engine and the FI system are quite familiar with each other. Of course, I do not know how it ran before I acquired it.

I did not have the chance to check the pk/n wires but I am 99% sure I left them open.

[Bill usn-1]

You need to warm it up some.

If the idle does not come down then you need to find out why.
It should be down to about 500rpm with the IAC closed.
The only way the idle will remain high is if the engine gets enough air to run it that high.
So where is it getting air from?

Was the IAC buzzing when you disconnected it?
You still had the key on with the jumper in, correct?

If so then you should be able to look in the hole above the IAC, with the aircleaner removed, and see the tip of the IAC.
There should also be no sucking of air in the top of that hole if the IAC is closed.
You said it would settle down into a normal idle before so I would assume the IAC is working and all is good.

But just incase the IAC is closed but the idle is still high..... see below


If all is good then you need to start looking for vacuum leaks.
Disconnect every vacuum hose from the motor except the MAP senso and plug them.

Then use brake cleaner and lightly spray around the TBI and manifold and see if the idle speed changes.