over fueling at idle

[kingsfisherman]

Hello,
I have had this problem for some time and done some parts chasing as well, at cold start up after a few seconds the engine loads up and black smoke comes out the exhaust. I hear a strong vacuum sound during this time and usually I add throttle to clear it up and get it smoothed out. After warming up to temp the loud vacuum, sound goes away and it idles fine, the other thing that happens during cold start up is the idle wont come down from when I throttle up, even if I move the linkage, again once it's warmed up it acts normal and idles down when the throttle is pulled back. If I pull the flame arrestor there after warm up I see lots of fuel in the TBI and even have seen it dripping out from under the flame arrestor.

Any ideas what causing the over fueling during cold start up?

 

[jimmbo]

If it was a Carb, it would be easy to diagnose, EFI on the other hand, is the worst of Voodoo and Black Magic.
If the engine is a 98, I doubt it would have O2 sensors, so it doesn't run a in a Closed Loop, but just uses basic things like Ambient and Engine Temps to adjust the AF ratio.
Being that the Flame Arrestor is above the TBI injectors how would Fuel be going upwards? Is there an Enrichment System separate from the usual TBI Injectors?

 

[kingsfisherman]

here is a pic of one time it frothed up, almost looked like frost

 

[jimmbo]

Okay the Injectors are higher up than I realized. That "looks like Frost" is exactly that, Ice. Humidity Levels must near 100% at the time

 

[kingsfisherman]

more pics of TBI after over fueling

 

[jimmbo]

I suspect that once the engine has warmed up, that ice melts and proper Airflow resumes

 

[kingsfisherman]

I suspect that once the engine has warmed up, that ice melts and proper Airflow resumes

It's very concerning when it drips from the TBI , the first time I noticed was when there was a puddle of fuel on the intake

 

[jimmbo]

If the Injector isn't closing completely, it will drip. A can of Miracle Elixir might remove any deposits on the Pintle, but replacement is usually the fix.

 

[kingsfisherman]

If the Injector isn't closing completely, it will drip. A can of Miracle Elixir might remove any deposits on the Pintle, but replacement is usually the fix.

I have another fuel meter body with new injectors and regulator, going to try that.

 

[jimmbo]

Is it USCG compliant?

 

[kingsfisherman]

Is it USCG compliant?

yes, it's actually the original fuel metering body that I switched out with a new Volvo Penta fuel metering body that I got off Ebay years ago, since then I have bought new injectors and rebuilt kit for the old one, just looking for a OEM GM pressure regulator diaphragm for it.

 

[kingsfisherman]

I did the clear hose test from the VSR to the pulse limiter to see if raw fuel is coming from the VSR, and after idling for a minute I started seeing fuel collecting in the hose

 

[kingsfisherman]

I noticed in my service manual the fuel flow diagram that my set up does not use the F fitting and hose route, my vent hose goes from the VSR to the pulse limiter at the TBI and the PVC hose goes to the flame arrestor. Any idea if my set up is wrong?

 

[QBhoy]

Maybe I’m being silly here. But are you sure that’s not emulsified oil coming up there ? Or maybe even as a result of a poor breather pipe work function ? How’s the IAC function and fixtures?

 

[kingsfisherman]

Maybe I’m being silly here. But are you sure that’s not emulsified oil coming up there ? Or maybe even as a result of a poor breather pipe work function ? How’s the IAC function and fixtures?

IAC seems to work, haven't done any tests yet but by the way it idles seems good

Maybe I’m being silly here. But are you sure that’s not emulsified oil coming up there ? Or maybe even as a result of a poor breather pipe work function ? How’s the IAC function and fixtures?

also have good fuel pump pressures, tested wires from ECU to ECT sensor achecked TPS with Ohm meter, tried changing the pressure regulator diaphragm but that only gave 22psi fuel pressure on the high side and it wouldn't run right then not at all so I switched it back.