4.3 GXI won't run

[CJK440]

I bought an 06 four winns with a 4.3 GXI knowing it had engine control system troubles. It will not fire at idle but I can get it to fire with 50% throttle. Once it fires I can only keep is sorta running by goosing the throttle continuously (almost like a carb that would only run on the accel pump). I did get it to stay running around 3000 rpm with stationary throttle for a few seconds but the engine yoyo'ed from 2000-4000 while popping thru the throttle body occasionally until it stalled out.

Here's what I did so far.

Checked fuel pressure low side fuel pressure was 7 psi, High side was 55
Popped out the fuel pressure regulator and changed the screen (had some paint chips but not horrible) with the E clip as per service bulletin
Changed the ignition parts, cap, rotor, wires and plugs.
Pumped some gas out of the schrader valve into a container to look for water seperation. none
Disconnected the fuel feed line and ran it off good gas in a gas can (after purging the fuel pumps of the previous fuel)

None of this made a bit of difference.



A couple of things I am wondering about.

Could the fuel injectors be plugged from fuel pump cell paint that was seen on the regulator screen? I would imagine unless most of the injectors were blocked it would at least run but rough.

IAC? I would figure if it was an issue it would be at idle and be out of the picture at higher RPM's.

Throttle position sensor?

MAP sensor?

There is not much else other than the ECM right?

If the fuel filter was clogged i would think I would have bad pressure readings.

I did proactively buy a clone fuel pump module but based on the pressure readings I am not sure of the value in swapping it.

If this was an OBDII auto I'd at least have some clues based on codes but as far as I know there is no way to pull codes without an expensive scanner. Unless there is some way to jumper a diagnostic connector and watch a testlight blink or something like that.

 

[alldodge]

You need a Rinda scanner to check for codes, but with it not being able to idle, my first thought is the IAC. You can remove it, and try cleaning. Use only soap and water and no carb cleaner or solvents.

Its a GXI what?

 

[CJK440]

gxi-f. Without data I did the shotgun approach and bought an iac, map & tp sensor. But will replace one by one to see what the culprit is.

 

[BRICH1260]

I’d double check the distributor timing by putting in TDC and removing dist cap and making sure rotor is pointing close to #1 cap terminal. Also don’t forget to check crankshaft position indicator and dist position indicator. On a GXI if any one sensor is off, it can make it difficult to start or run. I doubt the injectors are clogged.

 

[alldodge]

Clean the IAC then let us know what if any changes

 

[CJK440]

Considering how much the price dropped when the seller couldn't get it started I have a decent budget to throw parts at it (even though I hate doing that).

I will try Crank and Cam pos sensors after I clean the IAC.

I also have a new IAC, MAP, TPS and ignition module on order.....

Mechanically it sounds fine when it fires. I look forward to finding the root cause and hope its not ECM related.....

 

[89retta]

I see that you noted that you have the e clip as per the service bulletin. However you also said that you cleaned the screen. According to the service bulletin the screen is removed and discarded as the e clip replaces it . From what I remember

 

[89retta]

This is from the bulletin . Remove the screen on earlier engines when
replacing the regulator. Replace the screen
with the e-clip

 

[CJK440]

Yeah, I removed the screen.

For those keeping score at home, the iac pintle only has a tiny bit of buildup that was removed with a paper towel. Didn't make a difference. Neither did new crack and cam position sensors.

 

[QBhoy]

How’s the state of the fuel it’s feeding off ?

 

[CJK440]

How’s the state of the fuel it’s feeding off ?

I pumped some out and it didn't look contaminated with water. I also ran a hose from the pump to a 5 gal jug of good gas, ran the pumps with a hose off the rail to flush the tank gas in the system. Didn't make a difference.


No matter what I did, the engine will not fire at all with the throttle at idle, not even a hiccup. I can coax it to fire with 50% throttle and can keep it running albeit rough by goosing the throttle.

 

[89retta]

Have you changed the cap and rotor ?

 

[CJK440]

Have you changed the cap and rotor ?

Yes. Cap, rotor, wires and plugs.

 

[CJK440]

'twas the map sensor. When I replaced it, it fired right up.

 

[89retta]

Good to hear happy boating