Hard to start

Tiny
PITTERSDAD
  • MEMBER
  • 1998 CHEVROLET S-10
  • 4 CYL
  • 2WD
  • MANUAL
  • 216,000 MILES
My engine cranks excessively before starting. Backfire and sputtering noises while starting. Runs very rough while cold if you try to drive. Surging/sputtering and check engine sometimes comes on and blinks. If I let the engine heat up completely it seems to run fine. All gauges read normal. Recently replaced 02 sensor, egr valve, vac line from egr valve back to engine, catalytic converter and exhaust manifold.
Saturday, December 20th, 2008 AT 5:08 AM

45 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Check the fuel pressure and test the coolant temperature sensor, also scan the computer for OBD2 code/s then comeback.

This guide can help us fix it

https://www.2carpros.com/articles/engine-cranks-excessively-before-starting

Please run down this guide and report back.
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Saturday, December 20th, 2008 AT 6:12 AM
Tiny
MICHAELPBACKLASH
  • MEMBER
  • 1 POST
  • 1998 CHEVROLET S-10
  • 4 CYL
  • 2WD
  • MANUAL
  • 105,000 MILES
Sometimes my engine bucks back when starting hot or cold. No fluid leaks are aparent and gas milage is good. Performance has not been afected.
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Wednesday, May 20th, 2020 AT 12:42 PM (Merged)
Tiny
MMPRINCE4000
  • MECHANIC
  • 8,548 POSTS
Start by checking the cold start valve. This valve (actually an injector in the intake) adds additional fuel to engine during cranking. If malfunctioning it can cause long starts, or bucking.

Start by disconnecting the connector, if you notice any change, then use a noid light to see if it is getting power during cranking (it is only active during cranking).

Also check fuel pressure regulator for the presence of gas in vacuum line.

If problem persists, check fuel pressure with a mechanical gauge. With gauge attached to test port, turn ign. To ON and fuel pressure should go up to 40-45psi and hold that pressure for a couple minutes, if it goes down quickly, then FPR or a leaking injector.
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Wednesday, May 20th, 2020 AT 12:42 PM (Merged)
Tiny
RLUNOW
  • MEMBER
  • 2 POSTS
  • 1997 CHEVROLET S-10
  • 6 CYL
  • 4WD
  • MANUAL
  • 60,000 MILES
97 s10 engine starts hard ( a lot of cranking) after engine temp has been reached, also notice hard starting when the ac is on?
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Wednesday, May 20th, 2020 AT 12:42 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Do a fuel pressure check make sure its within specs and test the fuel pump relay come back with some results.
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Wednesday, May 20th, 2020 AT 12:42 PM (Merged)
Tiny
RLUNOW
  • MEMBER
  • 2 POSTS
I have 63lbs when the key is turned on and about 55lbs while it is running. Should it retain any pressure after the pump cycles when the key is turned on?
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Wednesday, May 20th, 2020 AT 12:42 PM (Merged)
Tiny
CHEVY DUDE
  • MEMBER
  • 2 POSTS
  • 1997 CHEVROLET S-10
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 105,000 MILES
Sometimes it starts fine and sometimes it cranks for a while. Put on a new fuel filter last week.
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Wednesday, May 20th, 2020 AT 12:42 PM (Merged)
Tiny
BLACKOP555
  • MECHANIC
  • 10,371 POSTS
Does it matter the temperature of the engine, temperature of the air outside, moisture in air, time of day?
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Wednesday, May 20th, 2020 AT 12:42 PM (Merged)
Tiny
CHEVY DUDE
  • MEMBER
  • 2 POSTS
Cold engine, 45 degrees, dry at 5:00 a.M.
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Wednesday, May 20th, 2020 AT 12:42 PM (Merged)
Tiny
BLACKOP555
  • MECHANIC
  • 10,371 POSTS
And it doesn't always do it under those conditions?

Does it get better when its say 50-60 degrees, or worse when its 0-30 degrees?
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Wednesday, May 20th, 2020 AT 12:42 PM (Merged)
Tiny
NTL1991
  • MEMBER
  • 16 POSTS
  • 1997 CHEVROLET S-10
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 172,000 MILES
Here's my problem. The engine cranks for about 5 seconds, then either dies or starts very rough and stalls. Immediately after, when cranking for a second time, the engine starts perfectly after 1-2 seconds with a good idle. Could the Oil Pressure switch that cuts power to the fuel pump when the pressure is too low be the culprit? If I keep cranking to get the pressure up, it stalls, and then immediately after crank again and the pressure is high enough, it'll start. It ALWAYS starts on the second start. Is there a bypass to the sensor when the starter is engaged?
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Wednesday, May 20th, 2020 AT 12:42 PM (Merged)
Tiny
2CARPRO JACK
  • MECHANIC
  • 11,533 POSTS
More likely you have a blown fuel pressure regulator that is dumping raw fuel into the engine causing the misfire and the lack of fuel pressure on initial start up. If you remove the upper intake (plastic cover) the reg is on the pass side, if it is gas washed under it, the reg is bad.
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Wednesday, May 20th, 2020 AT 12:42 PM (Merged)
Tiny
NTL1991
  • MEMBER
  • 16 POSTS
Well, the truck is only getting about 10 mpg as it is, might that also point to a blown fuel pressure reg? By the way, the engine is brand new (reman) with only 2500 miles on it. The intake manifold is new, also.

Thanks,
Nick
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Wednesday, May 20th, 2020 AT 12:42 PM (Merged)
Tiny
2CARPRO JACK
  • MECHANIC
  • 11,533 POSTS
That again points to the regulator being blown.I would check it out so you dont wind up gas-washing the cylinders and hurting your new engine
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Wednesday, May 20th, 2020 AT 12:42 PM (Merged)
Tiny
NTL1991
  • MEMBER
  • 16 POSTS
I do have a fuel pressure tester, are there any tests I could run before I go in and take the intake manifold off?

Thanks
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Wednesday, May 20th, 2020 AT 12:42 PM (Merged)
Tiny
2CARPRO JACK
  • MECHANIC
  • 11,533 POSTS
If the fuel pressure doesnt jump up when the engine is reved, the reg is bad.
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Wednesday, May 20th, 2020 AT 12:43 PM (Merged)
Tiny
NTL1991
  • MEMBER
  • 16 POSTS
It jumps up to about 65-68 psi from an idle psi of about 57. The pressure is also stable when the engine is turned off, no drops, etc.

The engine revs perfectly even up to Redline without a miss or anything.
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Wednesday, May 20th, 2020 AT 12:43 PM (Merged)
Tiny
2CARPRO JACK
  • MECHANIC
  • 11,533 POSTS
Could be an injector bleeding down over time. Leave the gauge on it to see what hapens to the pressure. Might even be a bad oring in the fuel/injector block in the intake
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Wednesday, May 20th, 2020 AT 12:43 PM (Merged)
Tiny
NTL1991
  • MEMBER
  • 16 POSTS
After shutting the engine off with a fuel pressure reading of about 61 PSI, 5 to 10 minutes later, the pressure is down to about 45 PSI.

Does this signal a leaky injector? What's my next step?

Thanks,
Nick
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Wednesday, May 20th, 2020 AT 12:43 PM (Merged)
Tiny
2CARPRO JACK
  • MECHANIC
  • 11,533 POSTS
Still might be a leaky regulator.I have actually pulled out the injector nozzles and rested them on dry rags to see if any of them were leaking down.
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Wednesday, May 20th, 2020 AT 12:43 PM (Merged)

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