Won' t start

chevrolet
1500

#1

99 suburban. X 1+ year progressively harder to start. Will turn over, but seems like it is not getting gas. Engine replaced 10k ago after I blew the last one at 220k. Did this before and after replacement. Once started runs fine. Can hear fuel pump kick on when key turned to on position. ?fuel relay?


#2

I would start with checking fuel pressure. Key on engine off 60-66 PSI. Key on engine running should be around 55 PSI. If you hear the fuel pump running, then chances are it’s not the relay. Is it hard to start cold? How about warmed up?


#3

After running it for a bit, does fine. After it sits, That is when the problem occurs.


#4

Next time floor the accelerator as you turn the key. If that gets it to fire up check for a leaking fuel pressure regulator and/or leaking fuel injectors.

If flooring it doesn’t work, energize the pump 8-10 times without cranking (just turn key on-off-on-off letting the pump run each time). If that works then you probably have a bad check valve in the fuel pump. Then you live with it or replace the pump.

If neither of those things does any good, get a spark tester and make sure you have spark. Then check back in.


#5

Turning the key 7-10 times and flooring it do seem to help.


#6

Doubt fuel injectors given it did it with both engines. Replacement engine came out of wrecked vehicle with 17 k on it.


#7

The replacement engine only might have come with the fuel injectors intact. Its often the case that all of your old stuff would be swapped over.

Anyway, find the fuel pressure regulator and after you’ve been running it at a time when this is likely to happen, pull the vacuum line from the regulator. If you find gasoline in the vacuum line replace the regulator.

Also experiment some more. The two things I said to try are for opposite kinds of problems. Flooring it is a flood clearing procedure which should get it to fire up if its getting flooded from leaking gasoline. I.e. that is a too much fuel issue.

The turn the key on-off-on-off is about a bad check valve in the fuel pump. When the truck is shut down hot the fuel would be running back to the tank and the fuel line would not only lose pressure but it would now be full of something like a combination of liquid fuel (which is all it should be), fuel vapor (not good), and air (bad). So this is too little fuel.

So try one or the other - either the flooring it, or the pump priming to see if its only one of those things that works.


#8

Fuel pressure regulator’s located inside the intake manifold. You can have a look at the regulator by removing the throttle body. The big problem is the regulator leaks fuel in the intake. After it gets warmed up then it gets shut off for a while. While it’s sitting there shut off, it’s leaking fuel out of the hole the vacuum line should be on, but since it’s located inside the manifold no vac line. When you go to start it back up it’s flooded. That’s why you can start it back up if you floor the pedal. That’s the “clear flood” mode. What you’ll se when you remove the throttle body is probably going to be mostly black and if the regulator is leaking you’ll have a nice clean spot, maybe even wet with gas under where the regulator would be leaking.


#9

Checked pressure. Only about 45. Cycle key and pump several times and pressure54, will almost start. Pour a bit of gas in from above, will fire up and run with a pressure of 54. Pretty sure now it is the fuel pump.