Help! my Suburban runs like crap

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pollac17

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I love Suburbans but I just bought a 99 5.7L that was difficult to get started. It would run awesome once it was going but then it would hard start even if it was warm sometimes. The check engine light is on and the scan shows 1345 error (crankshaft to camshaft position correlation fault).

by the way already tested fuel pressure it holds very well at 55-60 psi.

ok so I changed the crankshaft position sensor thinking that would do the trick but no effect.

Then I assumed the distributor was amiss so I grabbed on to it to see if it was loose. It was kind of loose and it actually rotated without adjusting the bolt with that horseshoe collar thing under it.

Now it starts like crap and runs like crap. It doesn't even idle well, it kind of falters. Something is way off and Im pretty much stuck. I tried putting the distributor back in the exact same position but it didn't help, I guess I wasn't accurate enough.

Help please. Thank you so much. -Brad.
 
Ok mine is the 5.7 vortec on a 99 so I suppose need to use the scanner as seen in the first video. In order to get it to the shop though I need to get it started somehow and the distributor is out of whack so I can't get it started.
 
I'm going to try to start it tomorrow and drive slowly to a shop with a scanner. Last time I drove it to test if the timing was correct on the distributor it ran horribly and was even vibrating the truck a bit.

Also, I changed both the crank sensor and the cam sensor. Still get the error and the distributor is out of adjustment.

I thought I could just wing it and get the distributor close enough but that is turning out to be nearly impossible
 
I got the truck running by moving the distributor a little at a time and then running the starter. It took a little while but I was able to drive it to the shop. They pulled the distributor and discovered that it was one tooth off. Now the distributor is in the right spot and there is no error message. The truck runs very well now but still kind of hard to start.
 
The outside temperature is 18 degrees right now and the thermometer on the truck says 30 degrees. Does this effect start up? It takes a little while to start the truck when its cold. Is that thermometer throwing things off?
 
the ecm doesnt use the car thermometer it uses an engine sensor. how up to date is the maintenance on the vehicle, are the plugs not worn, is the air filter clean?
 
It runs like a top once its started up now. plugs and wires new, distributor new, air filter new. No check engine light. Its just really hard to start up.

The fuel filter and fuel pump are both new. The fuel pump is an air-tech though and I think its junk.

I am replacing the fuel pump with a delphi and we will see if that fixes it.

Any other ideas? or you think its the fuel pump as well?

Thank you.
 
Don't just throw parts at it. Have you measured fuel pressure? Could be the FPR.
 
I know what you mean about not throwing parts at it but I really think its the fuel pump. I checked fuel pressure with a gauge and it was showing 60 when I turned the key so I thought it was fine, HOWEVER I had someone far more experienced than me look at the readings and they told me the pressure was "falling off too fast" and that the check valve at the pump was probably faulty. He said only use delphi pumps on these suburbans.

I drove the truck all day today to burn some fuel away so it isn't full when I drop the tank.

I also found out that it starts up fairly easily when the engine is warmed up, but still doesn't start like it should, not like my other 99 suburban which goes beast mode as soon as you turn the key.

Anyways I have a delphi pump and Im going to install it asap. I will let you know what it does.

If this doesn't work I will try the fuel pressure regulator like you said. BUT it runs so well after its started, just like my other suburban. I feel like a bad fpr would cause stalling or faltering...

Thank you for your help.
 
High of 12 degreesF tomorrow and windy but so help me I am putting in this fuel pump.
 
pollac17 said:
If this doesn't work I will try the fuel pressure regulator like you said. BUT it runs so well after its started, just like my other suburban. I feel like a bad fpr would cause stalling or faltering...

Thank you for your help.
Click to expand...

My bad FPR caused hard starting, but once it did it ran fine.
 
Found two other causes for hard cold start, EGR valve stuck open and EVAP system not functioning correctly causing an over rich mixture at cold start up
 
alright so this is taking longer than I thought to switch fuel pumps. My rubber hoses that come from my filler neck are impossible to remove and in bad shape so I am getting new ones tomorrow. Hopefully I can complete the switch tomorrow and give it a try.
 
Thank you, I could imagine that a bad fpr could leak fuel into the vacuum line causing fuel pressure to fall off quickly. The fpr will be the next thing I check if this new fuel pump doesn't solve the problem.
 
why arent you doing a fuel pressure test before going through all this work?
you remove the vacuum line on the FPR, if no gasoline in the vacuum line there is nothing wrong with it.
 
UPDATE: The new delphi fuel pump has been installed and the truck starts instantly in 5 degree Michigan weather.

In conclusion. DO NOT USE AIRTEX FUEL PUMPS for suburbans. Use a delphi and save yourself a lot of aggravation.

When you do your fuel pressure test your fuel pressure needs to hold at 55-60 psi WITH THE ENGINE TURNED OFF. If the pressure is not holding well you probably have a bad check valve at the fuel pump and your fuel pump needs to be replaced.

A bad check valve at fuel pump will give you hard starts.
 
How hard was it to change the fuel pump. My truck runs fine but the pump started making loud whining noise last week. I've done it before on a car and the tank removal as a pain. I'm a little scared to do this myself because of that, but mechanic wants money I dont have. Truck has 252k miles on it and that's about the only thing I haven't replaced or tweaked since I bought it last fall. Just towed a camper 2000 miles with it. Awesome thing.
 
hey sorry for the late reply. It is a pain for sure because you have to drop the tank and its huge. Drain the tank first. Or do it when you have like a few gallons in there, not 33 or something. Don't drop it all the way at first either because it will rip your wiring and your fuels lines. you have to position a jack underneath the tank so it drops just enough to reach under and disconnect the wires.

But seriously, do a fuel pressure test and if your fuel pressure goes to 60 and doesn't drop off quickly then you have a good working pump, I would run with it.

You can also cut a hole in the back there and pull the fuel pump out that way and not even drop the tank. My friend did it that way.
 
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