Idle issue and long cranking times

[Mean Green]

Alright guys, here's the symptoms my 1994 GMC Sierra K2500 (350 TBI / 4L60E) has been having the last few weeks or so. I have a pretty good idea of what the culprit may be, but id like some input from all of you.

1. This truck has always fired up quickly on a cold start, but recently it has been taking a bit longer then usual to start on a cold engine. After the first start of the day, it fires quickly with a warm engine.

2. At freeway speeds (2100-2400 RPM's) every so often the engine will miss. This is not really even noticeable at lower RPM's, however it will miss slightly once and a great while, while under load at lower RPM's.

3. If you get on the throttle (say 3/4 - WOT) the engine will stumble before picking up.

4. The last week or so, occasionally the engine will die when shifting out of park at idle. Restarting it and giving it some throttle will remedy this issue.


So there is where im at as far as what the truck is doing. I've replaced the fuel filter and spark plugs within the last 3000 miles, both of which where AC Delco. I have not yet checked the fuel pressure.

My thoughts are possible the following;
Throttle Position Sensor
Ignition Coil
Ignition Control Module
IAC Valve
Bad Injector?
Fuel Pump (Worst Case Scenario)

Thanks in advance guys!!

 

[Horns]

I would check fuel pressure. It sounds like your pump is getting weak.

-Sent from my twin turbo Desire using diesel fuel.-

 

[Mean Green]

I agree, i plan to check the pressure, I was just hoping I wouldn't have to replace the fuel pump at a 136,*** miles! Wishful thinking

 

[Mean Green]

Also, I forgot to mention that it did throw a SES light 2 days in a row after driving about 5 minutes. Then after the truck was shut off and restarted it did not throw the light again. I do not have a OBDI Scan tool, so I dont know what code it threw.

 

[Horns]

The pump in my 94 went at 103k miles. But that was after sitting for two weeks.

-Sent from my twin turbo Desire using diesel fuel.-

 

[Mean Green]

The pump in my 94 went at 103k miles. But that was after sitting for two weeks.

-Sent from my twin turbo Desire using diesel fuel.-

If its the pump, im for surely installing a Delphi pump. Learned that lesson a long time ago! Its not worth the little saving on buying a cheap chinnesse unit and have to worry about it failing prematurely!

 

[Horns]

If its the pump, im for surely installing a Delphi pump. Learned that lesson a long time ago! Its not worth the little saving on buying a cheap chinnesse unit and have to worry about it failing prematurely!

If your actual sending unit is in good shape then you can change only the pump on our trucks. The Delphi pump is usually only about $20 more ($70) then the cheapo ones at most parts stores.

-Sent from my twin turbo Desire using diesel fuel.-

 

[dirtridinz71]

You do not need a OBD1 scan tool just use a paperclip or small wire to jump the terminals. It will still give you the code. I would also consider the CTS (coolant temp sensor), on the intake manifold.

 

[ChrisAU]

I would check fuel pressure. It sounds like your pump is getting weak.

-Sent from my twin turbo Desire using diesel fuel.-

I came here to post this just by reading the title of the thread!

 

[Mean Green]

You do not need a OBD1 scan tool just use a paperclip or small wire to jump the terminals. It will still give you the code. I would also consider the CTS (coolant temp sensor), on the intake manifold.

I was aware of this trick for pulling the code for when the brake idiot light comes on, but forgot that worked for the SES light too! Thanks for the tip!