Longer cranking time to start

Tiny
TERMAXCO
  • MEMBER
  • 1987 CHEVROLET CELEBRITY
  • 2.5L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 85,000 MILES
Throttle body injector with single fuel injector spray nozzle on top in center.

Car sat for a few years but now has been driven for a year. The engine cranks good and has been starting quickly. Suddenly it has begun to require some longer cranking time and hard start as if not getting enough fuel. Also, sometimes it still starts on first try but upon random, but often occasions it requires several tries before it finally starts.
The number of tries it takes is also a random amount during which, engine may begin to run briefly and then go back to just cranking by starter as if it's not getting enough fuel to stay running. What has me confused is that, so far, it always eventually starts and then runs fine for as long as needed. Only the starting is being affected.

I can hear the fuel pump in gas tank pump up and stop when turn ignition on; I can see visible fuel spray into throttle body when cranking but I can’t say yet if it's a good enough spray pattern. Fuel filter seems to be clean. No outlet valve to check fuel pressure so, have not done so yet.

I’m assuming soon it may stop starting but, to date, since it always finally starts and runs fine, can I conclude its getting fuel and fuel pressure and spark? It's got a fairly new ignition control module when recently it had no spark. Crank sensor and coils are not new.
Or does it take more fuel to start than to run? I assume there is no partial spark problem just on starting.
Otherwise, all I can think of is if the fuel injector nozzle spray pattern is not atomized enough for an easy start and when the engine gets running, it can then use the fuel that way? But evidently, it's not filing out the plugs on starting?
Tuesday, December 28th, 2021 AT 7:30 PM

3 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,262 POSTS
What you described sounds more like a fuel pressure drop-off. Basically, pressure drops when the engine is off and then takes longer for the pump to build enough pressure for it to run.

This vehicle only requires fuel pressure between 9 and 13 PSI, so it's not extremely high, but still, it needs that amount. If the pump is weak or losing its prime, this can happen.

So, here is what I want you to try. Do this each time you start the vehicle to see if it starts normally.

1) Turn the key from off to the run position (engine off) and count to 5.

2) Turn the key off and repeat step 1 four more times.

3) On the fifth time, see if it starts normally.

Try this and let me know the results.

Also, I attached the directions for this vehicle when checking fuel pressure. The tester will need to be between the fuel filter and the fuel tank.

Let me know what you find or if you have other questions.

Take care,

Joe

See pic below.
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Tuesday, December 28th, 2021 AT 8:30 PM
Tiny
TERMAXCO
  • MEMBER
  • 54 POSTS
That Sounds right! Weak or lost prime and that would be why I am hearing the pump run now vs before; but it's still able to build up and hold eventually to start and run the engine.

So, I tried starting the car; and, then I tried giving the pump 5 times to pump up like you suggested to compare starting times etc. Today was a good starting day so did not see any difference, but I did hear the pump running for 4 of the 5 times (shorter duration each time) and on the fifth time it did not have to pump at all so, the pressure evidently got built up and held till starting. Will go to loaner program to borrow a pressure gauge but looks like you're right about the pump.
Thanks!

To double check: Does the gauge go in between the throttle body and the filter; or does it go between the pump (in the gas tank) and the filter (at the tank)? I.E, Does the test include or bypass the filter?
P.S: Can you believe the rear axle and suspension and then fuel tank has to be removed just to get to the pump? Give me my 55 Chevy back!

Thanks again!
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Wednesday, December 29th, 2021 AT 11:05 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,262 POSTS
Hi,

If I'm reading it correctly, it will go between the throttle body and filter. The gauge will need a hose that connects to both sides and has a Schrader valve in the middle for you to connect to.

I found a general pic from the internet so you have an idea of how it will look. You will need to determine how each side will connect to the line on the vehicle.

Let me know.

Joe

See pic below.
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Wednesday, December 29th, 2021 AT 4:15 PM

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