[Rambo_The_Dog]

I just bought a van with a 1989 GM 350 with TBI

It seems I have to open the butterfly's by stepping on the pedal to get it to start and symptom happens Hot/Cold ain:

I have a 1990 GM truck with a similar setup and NEVER have to step on the pedal to start it...Is the TPS sensor the likely culprit?

 

[curtis73]

Nope, sorry to say its a design flaw in the TBI engines. The TBI's injectors aren't really injectors at all. they use low pressure and they are more like squirt nozzles from a spray bottle. When its running sometime look down the throats and you'll see it squirting wet fuel on the throttles. During cold operation it takes a very long time for enough fumes to reach the chambers to start combustion.

I had an 88 TBI and some cold mornings I had to use starting fluid to get my EFI engine started. Its pathetic. I've heard that some have had luck at least reducing cranking times with new injectors. Evidently the old ones get more and more liquid-ish over the years. Some have claimed better starting with an aftermarket ignition box.

What is happening is when you're opening the throttles, the ECM is sensing it and injecting more fuel. In that manner it takes less time for the chambers to see fuel and ignite.

 

[nitro_baller4692]

the temp sensor could be reading the engine cold even if not causing the injector to put more fuel in the engine for a cold start,this causing the engine to want to flood.i would hook up a scanner to see what my temp reading is cold cause if it reads 12 degrees and you know it's 50 outside ,12degrees is causing it to read that it needs more fuel.

 

[sbchevfreak]

Also could be the IAC valve or control circut. Does it stay running immediatly after start, or do you need to keep your foot on the throttle for a minute?

 

[propaniac]

Pull the air cleaner and watch it run. I had a problem with the o-rings on the injectors. They would leak and dribble gas. Once you got it running it was ok but same hard to start as you described.

John

 

[Rambo_The_Dog]

Pull the air cleaner and watch it run. I had a problem with the o-rings on the injectors. They would leak and dribble gas. Once you got it running it was ok but same hard to start as you described.

John

Bingo! I think this is the problem. Combined with some old gas that was in the rig.

I probably should change out the fuel filter and get some o-rings, rebuild kit or new injectors?

What's the cheapest route to fix these?

 

[Rambo_The_Dog]

Update: Now a cold starting issue...

Bingo! I think this is the problem. Combined with some old gas that was in the rig.

I probably should change out the fuel filter and get some o-rings, rebuild kit or new injectors?

What's the cheapest route to fix these?

Well, I changed the fuel filter out and filled the tank with premium - ouch - and the truck is starting much better as I don't have to pump the pedal anymore but it won't keep running on a cold start until it warms up.

It starts right up after a few cranks of the engine but you have to keep your foot on the pedal feathering it enough to keep it running until it warms up enough and then the idle is ok - not great but ok...

I'd just take the darn thing in - but just bought a house an money is short and I am just hoping to troubleshoot a DIY low budget fix!

I still want to rebuild the o-rings on the injectors, because there looks to be leaking at idle - but I was wondering what else might be causing these cold start problems? Plugged EGR valve? Air Fuel Sensor? Computer?