97 C2500 5.7l Not Starting Easily In Cool Weather

rodram · March 31, 2009

Any thoughts here....? My 1997 Chev C2500 5.7L (208,000 km) is not starting easily on first startup on cool/cold mornings.... not at all at -20C or colder (that's below 0 Fahrenheit) unless the block heater is plugged in all night.... and now when the mornings are about -10C, it will start after several attempts (I only let the starter go for 3-4 seconds each attempt) and then it sputters and coughs for several seconds before it runs.... after starting, it runs great.... and other startups during the day are good on the first or second go at the starter.

Took it to my mechanic yesterday morning on the way to work and could not find anything wrong ... he kept it all night to be able to test it cold..... and this morning.... it started for him no problem, on the first crank on the starter... fuel pump at good pressure, all other tests conducted on ignition parts indicated nothing was wrong....

He suggests that the likely culprit is the fuel pump... but since it tested with the correct pressure, he was hesitant to replace it and charge me money for something I might not need right now... so now I have it back, no charge for the checking it out.

Should I just replace the fuel pump, wiring harness, filter... or keep risking another no start morning.....?

Mike G · April 3, 2009

When was your last tune up? I would look to maybe the disributor cap, or perhaps the fuel pressure regulator, since the guy at the shop says the pump pressure is good. Also, what about a bad O2 sensor. The electronic guys would know better, but if the computer is trying to meter mixture and that is going out, could cause problems.

My $.02s (in USD ) --Mike

pennzoil29 · April 3, 2009

When was your last tune up? I would look to maybe the disributor cap, or perhaps the fuel pressure regulator, since the guy at the shop says the pump pressure is good. Also, what about a bad O2 sensor. The electronic guys would know better, but if the computer is trying to meter mixture and that is going out, could cause problems.
My $.02s (in USD ) --Mike

That's a good start.

I gather the SES isn't on, since you've had it at the garage. I've seen crank sensors do this. I'm not saying that is causing your problem, but worth a check.

rodram · April 3, 2009

To Mike & Jeff... thanks for the suggestions.. my mechanic says that he has checked these things .... one other thing I have been told about relating to failure of a fuel pump is that the electrical contacts will wear and depending on what position the spinning fuel pump comes to a stop... there may be no contact or poor contact to get the fuel going when you try to start the next time ... and then when it does start to spin there is no problem ... says that if it fails like this you can get it going by having a friend thump on the gas task to provide a little shaking while you are cranking the engine .... saves a tow bill to the shop..... lol

When was your last tune up? I would look to maybe the disributor cap, or perhaps the fuel pressure regulator, since the guy at the shop says the pump pressure is good. Also, what about a bad O2 sensor. The electronic guys would know better, but if the computer is trying to meter mixture and that is going out, could cause problems.
My $.02s (in USD ) --Mike

That's a good start.

I gather the SES isn't on, since you've had it at the garage. I've seen crank sensors do this. I'm not saying that is causing your problem, but worth a check.

Mike G · April 6, 2009

Since it sounds like you have a pretty decent relationship with your mechanic, at the risk of a total dead vehicle issue, you may just want to do the pump. Usually that is a $350 (USD) repair at the dealerships, but if you can have it done for a little more than the cost of the pump, I'd have at it.

--Mike

rodram · April 7, 2009

Since it sounds like you have a pretty decent relationship with your mechanic, at the risk of a total dead vehicle issue, you may just want to do the pump. Usually that is a $350 (USD) repair at the dealerships, but if you can have it done for a little more than the cost of the pump, I'd have at it.
--Mike

Mike.... Thanks again .. I likely will get the fuel pump done.... funny thing though is, this week, the truck is starting no problem..... I guess it might be getting as tired of the Saskatchewan winter as much as I am....

Mike G · April 8, 2009

..... I guess it might be getting as tired of the Saskatchewan winter as much as I am....

Now that's some funny stuff. We just had snow all weekend here, now it's up to 60 degrees (f). Is that 29RLS the unit with the outdoor kitchen??? My wife thinks it's time to invest, of course, it means I need a bigger truck

--Mike

rodram · April 8, 2009

..... I guess it might be getting as tired of the Saskatchewan winter as much as I am....

Now that's some funny stuff. We just had snow all weekend here, now it's up to 60 degrees (f). Is that 29RLS the unit with the outdoor kitchen??? My wife thinks it's time to invest, of course, it means I need a bigger truck

--Mike

Mike... yes the trailer has the outdoor two burner propane and running hot&cold water , all under the awning . An excellent feature... last summer we did most of our cooking outside using this propane stove and a stand-alone propane BBQ that we brought along. Most of the Cougars have this outdoor kitchen now .. maybe all of them... the manufacturers have gone away from having the built-in outdoor BBQ attached to the trailer.

The 29RLS is 33 feet long, and great if most of your trailering is just for two, (it has a very large lounge/living space with a sofa that pulls out for an extra bed) If you are travelling with young kids most of the time there are other models with bunks in the back.... Check out the Cougar X-Lite models... they are several hundred pounds lighter than than the regular Cougars... I think they are GVW 7900lbs, and the dry weights vary around 6000 to 6500lbs

Anyways.... I think we are getting off topic.....for this forum

Mike G · April 8, 2009

We were looking at one of these with the bunks in the back (for more than two of us) and the outdoor kitchen on the rear passenger side corner, under a pull up awning/side panel.

rodram · April 13, 2009

OK.... back on topic again!

After reading up on the evolution of GM fuel injector systems, looking through my aftermarker repair manual, and checking various discussion threads on the net started by others with the same problem..... I came across reference in two places to a GM Service Bulletin 00-06-04-003B. This makes the most sense so far for the starting difficulty that I have experienced ...

The service bulletin is for owners of 4.3L, 5.0L, and 5.7 L in vehicles from 1996 to 2002

"... may experience a 'Service Engine Soon' light, misfire, rough idle or hard start due to a deposit build-up on the Sequential Central Port Fuel Injector (SCPI) POPPET VALVES. The deposit build up may cause injector poppets to stick closed. Certain fuels have been found to interact with the SCPI system to cause the deposit." Apparently, if you have a California vehicle with California emission control then GM will service and/or replace your injectors for a time period of up to 10 years...." It appears that if all else fails, then the ultimate fix is to replace the SCPI with the MFI assembly.... (which happens to be standard on the 7.4L engine I believe...)

Based on this, I can rationalize that the PCM is trying to enrich the fuel mixture to the injectors on cold start (as it is designed to do on the Sequential Central Port Injector (SCPI) system used on this engine starting in 1996). But if the injector poppet valves are restricted or not opening properly then the fuel is still not getting where it is needed for ignition. So the engine is trying to start with a very lean mixture or not enough fuel at all.

So.... I will put another slug of good injector cleaner in the tank and run it for awhile .... and then take it back to my mechanic for check the opening/closing function of the Injector Poppet Valves .....

obtw... there is also a curious little comment at the end of the Service Bulletin that says if the injector poppet deposits reoccur after the first cleaning... then "... replace the fuel tank fill pipe assembly" lol.