Help With Hard Starting '99 Silverado

Need some direction on my hard starting '99 Silverado 4X4 with 5.3L engine and auto transmission. VIN# 1GCEK14TXXZ105127 (in case this helps further identify). Truck has 100,000 miles (had about 97,000 miles when I bought 2.5 years ago). I've read a lot of other posts on this site, hopefully I've accumulated enough data to allow someone to steer me in the right direction. Bought the truck from the original owner. This truck doesn't get driven much and mostly sits in the garage. It's been hard to start from the beginning. You have to crank the engine over 2 or 3 times (turning ignition key off between crank sessions) to get the truck to start. Truck will eventually start with continuous cranking but I try to not do that to the starter. Plugs look good, I've changed the fuel filter, and the fuel pressure regulator with no improvement in starting. Truck sometimes starts better in really cold weather. Starting gets just a little worse with heat and is about the same even if truck is warmed up and shut of for short time. The fuel pressure regulator I bought was an Auto Zone item that was very difficult to get back in position to fasten it with the clip, I actually had to lightly file down the surface that goes against the fuel injector rail before I could get the clip in place. The new filter and pressure regulator had no impact on starting difficulty. The truck runs pretty well once it does get started. Might miss a few times as it initially gets warmed up but within a few seconds the engine idle evens out and it runs well throughout the RPM range.

Just got through doing some fuel pressure testing and here's the results:

Cold/warm start: after 2 or 3 seconds of cranking, fuel pressure eventually spikes to between 58-62 PSI. Fuel pressure bleeds off to 0 PSI in about 15 seconds after shutting engine off.

Running Fuel Pressure: with engine at idle steady fuel pressure is about 57 PSI

Fuel Pressure With Return Fuel Line Blocked: with engine running at idle, fuel pressure starts out at about 75 PSI but after 4 or 5 seconds the pressure gage starts fluctuating between 60-75 PSI. Could possibly be because I didn't want to ruin my return line by pinching it off too firmly.

If anyone has any suggestions what the most logical next step is I sure would appreciate them. Don't want to keep throwing time and money at it but am determine to fix what's needed to get it to start properly. At this point I'm not sure if its a singular item issue (another pressure regulator, fuel pump, injectors, or some random under hood sensor) or if it's likely a combination problem. Any help from you experts out there would be appreciated.

Need to check the ECT sensor (Engine cooling temp) for proper operation.

Fuel press bleeding off in 15 secs indicates a bad in-tank fuel pump check valve.

Need some direction on my hard starting '99 Silverado 4X4 with 5.3L engine and auto transmission. VIN# 1GCEK14TXXZ105127 (in case this helps further identify). Truck has 100,000 miles (had about 97,000 miles when I bought 2.5 years ago). I've read a lot of other posts on this site, hopefully I've accumulated enough data to allow someone to steer me in the right direction. Bought the truck from the original owner. This truck doesn't get driven much and mostly sits in the garage. It's been hard to start from the beginning. You have to crank the engine over 2 or 3 times (turning ignition key off between crank sessions) to get the truck to start. Truck will eventually start with continuous cranking but I try to not do that to the starter. Plugs look good, I've changed the fuel filter, and the fuel pressure regulator with no improvement in starting. Truck sometimes starts better in really cold weather. Starting gets just a little worse with heat and is about the same even if truck is warmed up and shut of for short time. The fuel pressure regulator I bought was an Auto Zone item that was very difficult to get back in position to fasten it with the clip, I actually had to lightly file down the surface that goes against the fuel injector rail before I could get the clip in place. The new filter and pressure regulator had no impact on starting difficulty. The truck runs pretty well once it does get started. Might miss a few times as it initially gets warmed up but within a few seconds the engine idle evens out and it runs well throughout the RPM range.

Just got through doing some fuel pressure testing and here's the results:

Cold/warm start: after 2 or 3 seconds of cranking, fuel pressure eventually spikes to between 58-62 PSI. Fuel pressure bleeds off to 0 PSI in about 15 seconds after shutting engine off.

Running Fuel Pressure: with engine at idle steady fuel pressure is about 57 PSI

Fuel Pressure With Return Fuel Line Blocked: with engine running at idle, fuel pressure starts out at about 75 PSI but after 4 or 5 seconds the pressure gage starts fluctuating between 60-75 PSI. Could possibly be because I didn't want to ruin my return line by pinching it off too firmly.

If anyone has any suggestions what the most logical next step is I sure would appreciate them. Don't want to keep throwing time and money at it but am determine to fix what's needed to get it to start properly. At this point I'm not sure if its a singular item issue (another pressure regulator, fuel pump, injectors, or some random under hood sensor) or if it's likely a combination problem. Any help from you experts out there would be appreciated.

good post with good info...I would try first some injector cleaner by techron...also use a few ounces of marvel mystery oil to the fuel tank. the rapid bleed down is the injectors dirty or the fuel pump check valve.. the pressures are normal so this is why the injector is suspect here...but still can be the pump...


the best way to be sure is put pressure guage on the fuel filter key on ignition see if it rapidly drops if so the pump is for sure N/G...

use the delphi fuel pump..do not use air tex.......

Thanks so much for the suggestions guys, a couple of more questions:

For 777stickman: where's the ECT sensor and is there a simple test that a simple person as myself can perform to check that it's working?

For j cat: do I pick up the techron injector cleaner and the marvel mystery oil at the local auto parts stores or do I need to order it online some where? How long should I give these additives to work (50 miles, 1 tank full, 2 tanks full) before assuming the problem requires new injectors.

As to putting the pressure gage online at the filter, I assume that's to rule out the potential bleed off impact of a bad injector and narrow the problem to the bad pump check valve 777stickman referenced? I think the borrowed pressure gage kit I'm using has a filter bypass hose and fitting so I think I can do that.

I'll keep you posted. Thanks again guys.

For j cat: I found where I can get the Marvel Mystery Oil and Chevron/Techron fuel injector cleaner. I'll get that tomorrow and get started burning some in the truck. Thanks for the tip.

Another question for the experts. If I do the fuel pressure test at the in line fuel filter and determine the issue is not the pump but is instead most likely an injector, does anyone have a suggestion as to the best way to determine the good injectors from the bad ones? I haven't priced them but I'm guessing I don't want to replace any more than I have to. thanks again guys.

For j cat: I found where I can get the Marvel Mystery Oil and Chevron/Techron fuel injector cleaner. I'll get that tomorrow and get started burning some in the truck. Thanks for the tip.

Another question for the experts. If I do the fuel pressure test at the in line fuel filter and determine the issue is not the pump but is instead most likely an injector, does anyone have a suggestion as to the best way to determine the good injectors from the bad ones? I haven't priced them but I'm guessing I don't want to replace any more than I have to. thanks again guys.

if the injectors are just dirty the cleaner with the marvel at 1 ounce per 10 gallons of fuel you should see the engine run smoother especially at idle with burning off a half tank of fuel...

don't want to go to the replacing the injectors..expensive stuff..

since we are forced to use alcohol mixed fuels this has water in it. when the vehicle sits for extented time 2-4 weeks in the humid weather condesation forms creating a sludge..this then damages the fuel system..

the use of these products I recommended will reduce these issues...especially when you plan on having the vehicle inactive for a time..

the injector treatment should be done at least every oil change .

since I am a boater with a mercrusier engine this has all been proven over the many years ....alcohol and humid weather is a very bad condition....

j cat, thanks again for the input. Guess I never really thought too much about inactivity creating fuel injector issues on the truck. I find it interesting that I'll go to great efforts to treat the fuel in my Harley and lawn mowers and snow thrower for extended winter storage but never gave a thought to the truck. Guess it speaks volumes about my mechanical savvy (or lack there of). Hope to get the fuel filter bypass pressure test done today and see if I can rule out the fuel pump part of the equation, then I'll get the additives tomorrow and we'll see what transpires. Thanks again for the help and have a great Labor Day.

The ECT Sensor is normally close to the thermostat housing. This was just a suggestion in my '98 manual for "hard starting". If you don't have any codes related to the ECT, then it's most likely OK. Best way to check it though is with an engine capable scan tool that will read the temp being sent to the VCM.

I really think that J caT is on the right track for your issue. Hope you follow his advice and let us know.

777stickman, thanks for the input. I appreciate you guys taking the time to try to help those of us less capable in all things mechanical. You guys are a big help. I used a buddy's code reader a few months ago and their were no recorded codes showing. I guess that would have been entirely too easy and taken all the fun out of this adventure. I'm headed out to the garage now to try to rule out the fuel pump as a culprit. If that checks out I'll indeed be trying j cat's suggestions. I'll be sure to report back on the results. Thanks again.

Note to all, finally was able to isolate the fule pump and test fuel pressure and bleed off of just the pump. Had a tough time getting necessary fittings to allow my fuel pressure gage to go in line in place of my fuel filter. Keyed pump on multiple times. Every time, the fuel pressure out of pump tested 70 psi, then the pressure bled off to 0 psi almost immediately (took about 5 seconds to bleed off). Based on previous discussions, 70 psi seems to be on the low end of pressure and as I understand things, the pressure should not be bleeding off this quickly. It appears to me that this indicates either the fuel pump is bad or I may have a leak in one of the lines coming from the tank. Since I've never seen any gas leaks under the truck, I assume the fuel pump must be going bad. Any body agree with this diagnosis? I just got the truck back up and running after doing some brake work so I'm going to run it for a while with the fuel cleaner and mystery oil but I would expect that the hard starting problem won't get better until I change the fuel pump. Just looking for a little consensus.

thanks for posting back with the test results. yes the fuel pump is N/G..buy a delphi fuel pump. do not buy airtex ...these fail quickly..3-6months...

yes the fittings to hook up AT FILTER , are /can be difficult to find....

BUT THAT IS THE WAY TO BE SURE...FUEL PUMPS ARE EXPENSIVE !

post back how it went . also check pressures when NEW pump is in !

Thanks for all the help. You guys are the best. Since the truck's not a daily driver I'll probably save the fuel pump replacement until after all my leaves fall (what a pain in the but October is with a wooded lot in Indiana). I will be sure to get the good brand and post results when I complete the installation.

Many times these fuel pumps are VIN specific. As stated the AC Delco/Delphi pumps are the way to go for durability. The link below is a good place to order from. Just drop them an e-mail with your full VIN number and they will send you back a part number for the correct pump. From there you can look up pricing.

http://www.gmpartsdirect.com/

I had no idea these fuel pumps were that VIN specific. Thanks for the input. I'll take your advice and head down that path.

I had no idea these fuel pumps were that VIN specific. Thanks for the input. I'll take your advice and head down that path.


your vehicle has only 2 fuel pumps that are oem designed for it.

one is with fuel evap emissions. the other is with no fuel evap controls.

If you live in the USA MOST likely the fuel evap emissions fuel pump assembly is whats required.

the vin #will show that info.