97 5.0l weird starting issue

[|WYG|SS]

my friend has a 97 1500 with 5.0l 4x4 automatic and recently he has been having problems with the truck starting. he has to do short quick turns of the key and sometimes it will start normally, other times he has to do the short quick turn of the key multiple times. his other friend who fixes cars on the side thinks it might be the fuel pump going bad. you can hear the fuel pump kicking in. what would you guys think might be wrong? or is it a common problem?

[CrazyLegs702]

try the fuel pressure regulator my 2000 had similar issue

[Blue Bowtie]

Tell your friend to turn the key on and wait two second while the fuel pump primes the lines and injector pod. Your friend should also test fuel pressure to verify at least 61 PSIG at the test fitting port near the left rear of the intake.

[|WYG|SS]

i was telling him to take it in and get it checked out to find the exact problem. he wants me to change the fuel pump but im telling him it doesnt sound like a fuel pump cause when one goes bad it will usually not work. but yeah i will check pressure. thanks guys

[iroc343]

Is this a fuel pump issue or a ignition switch problem? When he says he has to turn the key multiple times, is that to get the starter to crank or the fuel pump to run? I'd hate to have him change the fuel pump only to find the ignition switch is faulty.

[MT-2500]

Originally Posted by iroc343

Is this a fuel pump issue or a ignition switch problem? When he says he has to turn the key multiple times, is that to get the starter to crank or the fuel pump to run? I'd hate to have him change the fuel pump only to find the ignition switch is faulty.

It could be a lot of things.
But
Unless you just want to throw parts at it or try to out guess it.
You need to do some proper testing.
Like.
Does the fuel pump power/2 second prime up every time key is turned from off to on?
Does the dash power up key on every time?
When no start does it lose spark or fuel pressure?

Has the ign switch every been replaced?
97 is a bad year on ign switches but proper testing before throwing a switch at it.

As Blue Bowtie said check that fuel pressure.

Do as he outlined.
Also tape the gauge to windshield and drive it 30 minutes and confirm good fuel pressure running.

The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold or hot and fuel pressure testing guide lines.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak in system.
Post back fuel pressure readings.

[|WYG|SS]

here is what happens
-he has to turn the key like 10 short quick turns(starter is working) and it will start, dash lights do come on.
- i go take a look at it and it cranks up on one turn
-his friend has a scanner and scanned it and no codes
- couple days after scan his C/E light goes off,(O2 sensor fault) C/E went out now
- he says when truck gets warm it usually starts in 1 turn.
- he says no loss of power when i asked him
-you cant hear if fuel pump is charging cause of annoying beeping inside cab(i will throw my FPT on it to see if i can see it charging up.
- could if possibly be a bad Crank position sensor?(but wouldn't it throw a code)
-i might lean more towards the FPR cause o2 sensor fault.

i will check pressure and post to let you guys know what is going on

[|WYG|SS]

well the results are in he turned the key and it went up to about 57 and started it and stayed about 53 so i told him to try giving it some gas and stayed about 53. shouldnt it jump up a little when you give it some gas? it took him a couple turns of the key to start it. we had it running for about 1 min. so after we were done i just walked over and just turned the key(held it sown for about 3 sec) and it started. then i shut if off and tried it again and it started. so since he only does short quick turns i told him before work tomorrow to try holding it down for 3 sec and see how it starts. where is the fuel pressure regulator located?

[MT-2500]

Originally Posted by |WYG|SS

well the results are in he turned the key and it went up to about 57 and started it and stayed about 53 so i told him to try giving it some gas and stayed about 53. shouldnt it jump up a little when you give it some gas? it took him a couple turns of the key to start it. we had it running for about 1 min. so after we were done i just walked over and just turned the key(held it sown for about 3 sec) and it started. then i shut if off and tried it again and it started. so since he only does short quick turns i told him before work tomorrow to try holding it down for 3 sec and see how it starts. where is the fuel pressure regulator located?

Run the full fuel pressure test as outlined and post back pressure readings.

[|WYG|SS]

he turned the key and it went up to about 57 and after he started it and stayed about 53

[MT-2500]

Originally Posted by |WYG|SS

he turned the key and it went up to about 57 and after he started it and stayed about 53

That is not good.
Pressure to low on key on and or running.

But
That is not running the full test.

Run the full test as outlined.

Tape a fuel pressure gauge to outside mirror or outside windshield and drive for 20 to 30 minutes and watch pressure.

The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold or hot and fuel pressure testing guide lines.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak in system.
Post back fuel pressure readings.

[|WYG|SS]

ok i will try that tomorrw.




here is a nother thing i didnt mention. when the truck sits overnite it will be hard to start. i went outside on my break and tried starting the truck and didnt want to start. as i was starting it i would hold it down for like 3 sec and then turn key off. as i let off the truck was sounding like it is firing and then just die's, i even gave it some gas but no luck, then when it finnaly started after 7 times their was a pop in the exhaust which is common when trying to start it so many times.

i will see my friend tomorrow so i will check full test.

[MT-2500]

Originally Posted by |WYG|SS

ok i will try that tomorrw.




here is a nother thing i didnt mention. when the truck sits overnite it will be hard to start. i went outside on my break and tried starting the truck and didnt want to start. as i was starting it i would hold it down for like 3 sec and then turn key off. as i let off the truck was sounding like it is firing and then just die's, i even gave it some gas but no luck, then when it finnaly started after 7 times their was a pop in the exhaust which is common when trying to start it so many times.

i will see my friend tomorrow so i will check full test.

That is a very good reason and that is why you need to run the fuel pressure test.
You have to have good full fuel pressure or the injector will not squirt on a cold start.
You can not leave home without.
Low fuel pressure will give you a hard or no start.

[|WYG|SS]

well when it primed it went up to about 62 and when it was running it did about 53, took it down the road and everything and the max it went up to when giving it gas was about 65. i tried to pinch the return fuel line but since i was at work i only had a needle nose pliers with me and as i tried both no change at all (didnt know which one was the return line).

my friend had told me that he went up to the mechanic that i go to and he goes to, he told him it is the fuel pump. i told him just pay the money to have him run a test but the thing is he has none so thats why i trying to do it for him.

[|WYG|SS]

anything?