Hard start. (This problem happened over night)

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jonny
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Joined: Thu Sep 25, 2014 5:48 am
Location: Connecticut
Isuzu vehicle(s): 1995 Isuzu Pickup 2.3L 2wd 5 -speed 96,500.

Hard start. (This problem happened over night)

Post by jonny »

1995 Isuzu Pickup 2.3L 95k mi. 2wd FI.
Suddenly I have a hard start issue, after the truck always started instantly. I've replaced:
Fuel pump
Fuel filter
Fuel pressure regulator
Spark Plugs
Distrbtr. cap (rotor was really STUCK ON, so I left old one in place)
Cleaned MAF with Alcohol & MAF cleaner. (MAF looked really clean)
I also put 2 check valves in fuel line running from fuel pump to fuel rail, although the fuel pump has a built in check valve that is working.
When cranking, fuel pressure gets to 42 PSI. then “if” truck starts, PSI goes to 36 psi. & runs perfect. When I remove vacuum line from Fuel pressure reg., while it's running, fuel PSI jumps up to 42, as it should increase. There is no fuel in vacuum line (NEW Fuel pressure reg).
If I use a little ether/starting fluid, the truck always starts immediately.
Once the truck starts, usually after 9 tries of cranking, it always runs perfect. The "Choke circuit" (?) idles high until it warms up, then idles down & purrs. No hesitation while driving whatsoever. Once truck is warmed up, it starts immediately as well. If it sits for 4 hours or so, it is then 9 cranking tries to start it again.
I’ve spent about $200 throwing parts at it. It’s OBD-1 & the code is #34 ,which i get different opinions on what #34 is? “MAP”? Manifold Absolute Pressure?
Is 42 PSI a low pressure for truck to start up initially?
Any help?
THank you
1995 Isuzu Pickup/2.3L/ 5-speed/2WD/ gasoline' /FI/ OBD1/ 89,400mi.
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Red Truck
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Location: Vader, WA

Re: Hard start. (This problem happened over night)

Post by Red Truck »

My limited knowledge of FI is beyond dangerous, but I believe there's a specific Engine Temp Sensor somewhere, aside from the sensor that feeds the gauge. It tells the ECU how cold the engine is, so optimum fuel is delivered. I don't know where it is on your rig nor how to test one, other than swapping it out (Rock Auto, about $15).
'87 Isuzu p'up 2.3 gas, carb'd, 5spd, 4WD, base model, Fed spec
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JoeIsuzu
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Isuzu vehicle(s): Original owner, '83 LS Diesel, 5-spd, 2wd, Long Bed, restoration in progress!

Re: Hard start. (This problem happened over night)

Post by JoeIsuzu »

In consideration of those who may be able and willing to help --
This is also posted on the PlanetIsuzoo.com forum, and has some replies. I'd hate to see anyone spend time / research to provide an answer that's already been posted there.
https://forum.planetisuzoo.com/viewtopic.php?f=1&t=148151

Jack
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puttputtinpup
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Re: Hard start. (This problem happened over night)

Post by puttputtinpup »

Red Truck wrote:
Wed Apr 28, 2021 9:24 am
My limited knowledge of FI is beyond dangerous, but I believe there's a specific Engine Temp Sensor somewhere, aside from the sensor that feeds the gauge. It tells the ECU how cold the engine is, so optimum fuel is delivered. I don't know where it is on your rig nor how to test one, other than swapping it out (Rock Auto, about $15).
Sounds possible to me. My dad's 93 ford trk was sooo hard to start. You had to hold your foot at wide open to start then ran horribly. It was a sensor that told the ecm what temperature the engine was and adjusts the amt of fuel accordingly. Swapped sensors and was fine after that
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jonny
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Location: Connecticut
Isuzu vehicle(s): 1995 Isuzu Pickup 2.3L 2wd 5 -speed 96,500.

Re: Hard start. (This problem happened over night)

Post by jonny »

Problem fixed?
The vacuum line to the MAP sensor, located on inner fender to rear of battery was MISSING.
Might have fallen off, & where it T's in, was hiding.
1995 Isuzu Pickup/2.3L/ 5-speed/2WD/ gasoline' /FI/ OBD1/ 89,400mi.
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Red Truck
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Re: Hard start. (This problem happened over night)

Post by Red Truck »

I'll bet that's why your "MAF looked really clean"...it wasn't being used. Kinda like my lawn mower!! Good to hear you've found the problem. How that vacuum line vanished overnight might be another story, tho....R/
'87 Isuzu p'up 2.3 gas, carb'd, 5spd, 4WD, base model, Fed spec
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