Truck help!

Tiny
BGOERMAR80
  • MEMBER
  • 1993 CHEVROLET CHEYENNE
  • 4.3L
  • 6 CYL
  • 2WD
  • MANUAL
  • 200,000 MILES
I have a 93 Chevy Cheyenne 1500 4.3l v6 tbi about a
month ago I was driving down the road and my truck just
died I pulled over looked under the hood realized one of
my injectors wasn't fireing off so went to autozone got 2
new injectors still nothing so I got it home from a buddy
with a trailer I replaced the distributor and was able to
drive it it drove fine for about a day then I took it on the
highway and it started to loose power by the time I got to
work couldn't go over 35 mph so tried timing it and
nothing when the truck is idling it surges up and down
and it will barely move now please help
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Monday, December 28th, 2015 AT 7:25 PM

7 Replies

Tiny
CARADIODOC
  • EXPERT
You're going about this all wrong. The timing didn't magically change while you were driving so don't expect adjusting it to solve anything. If you suspect an injector problem, it's much more likely to find a stretched terminal in the plug, and it's making intermittent contact.

It's more likely you have a sensor that's failing. On almost all vehicles other than Chrysler products, the mass air flow sensor is the biggest player in the fuel metering calculations, and they have a pretty good track record for failures. There can't be any leaks or loose hose clamps in the fresh air tube between the MAF sensor and the throttle body. I can't remember for sure, but I seem to recall your engine doesn't use a mass air flow sensor. That means you can remove the fresh air tube / air filter and watch the spray pattern from the injectors. Look for one that stops spraying. If you DO have a MAF sensor, you can't watch the injectors because removing the fresh air tube stops the air from going through the sensor and being measured. You won't get any fuel commanded from the Engine Computer.

The place to start is by reading and recording any diagnostic fault codes. Those will indicate the circuit or system that needs further diagnosis, or the unacceptable operating condition.
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Monday, December 28th, 2015 AT 8:15 PM
Tiny
BGOERMAR80
  • MEMBER
Yes my truck doesn't have a mas
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Tuesday, December 29th, 2015 AT 5:42 AM
Tiny
CARADIODOC
  • EXPERT
The first thing is to read the fault codes.

https://www.2carpros.com/articles/buick-cadillac-chevy-gmc-oldsmobile-pontiac-gm-1983-1995-obd1-code-definitions-and-retrieval-method

This page tells you how to do this yourself, and what each code number means.

If there are no codes, look at the fresh air tube between the mass air flow sensor and the throttle body. All incoming air has to go through that sensor to be measured so the Engine Computer can calculate how much fuel is needed. If any air sneaks in through a leak, it won't be included in the fuel metering calculations. Common causes are a loose hose clamp and a hidden crack in the tube.

Please use punctuation in your replies, otherwise what you write can be read in three or four ways, and you know I'm going to interpret something wrong. "New injectors still nothing" doesn't describe anything. Be specific with the symptoms, as "still cranks but doesn't run" so I'm providing an answer to what is really happening.

If you feel there's no gas spraying from the injectors, be sure to check for spark too. By far the highest percentage of cranks / no-starts are caused by a loss of fuel AND spark, but too many people get stuck on the first thing they find and spend all their time in that circuit or system. If you have good spark with the crank / no-start, measure the fuel pressure and listen for the hum of the fuel pump for one second after turning on the ignition switch. If you hear that hum, and perhaps the engine runs for a few minutes, then fuel pressure drops off, you might suspect a plugged pick-up screen inside the gas tank. The additional clue is after stalling and sitting for a few minutes, that screen will often stretch out and allow fuel to pass again for another few minutes. When you have a fuel pressure regulator on the fuel rail on the engine or in the throttle body, the stalling usually occurs when the highest volume of fuel should be flowing through that screen, which is during coasting. Fuel starvation is less of a problem at highway speeds.

Also, since you originally had no fuel from just one injector, remove their plugs and squeeze the terminals to make a tighter contact.
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Tuesday, December 29th, 2015 AT 4:22 PM
Tiny
BGOERMAR80
  • MEMBER
Ok I actually tried to run the test codes last night and silly enough my check engine light wasn't on so I don't know where to start I have head that the map sensor could have something to do with it?
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Tuesday, December 29th, 2015 AT 4:59 PM
Tiny
CARADIODOC
  • EXPERT
Do you mean the light wasn't on while driving or it doesn't turn on for a five-second bulb check when you turn on the ignition switch? If it never turns on, either it's burned out or the computer isn't turning it on. For that, you'll need an older scanner to read the codes.

If the Check Engine light does turn on for the five-second bulb check, there still can be codes in memory. A lot of people mistakenly think there won't be any codes if the light isn't on while they're driving. In fact, the light only gets turned on when a fault code is related to something that could adversely affect emissions. Problems that result in a crank / no-start condition might be detected resulting in a fault code being set, but an engine that doesn't run can't have excessive emissions, so the Check Engine light would not be turned on.

Regardless, you'll need to find a scanner to check for fault codes. The people at most auto parts stores will do that for you for free, but their code readers usually only work on '96 and newer vehicles with the OBD2, (on-board diagnostics, version 2) emissions system. That's what all vehicles sold in the U.S. Starting with '96 models have. You might have to visit a mechanic who has an older scanner. You can find them on eBay too pretty cheap. I have a Monitor 4000 that I like very much. I also have a Chrysler DRB3. A lot of independent shops bought them because with an extra plug-in card, they will do emissions-related stuff on any brand of vehicle, but again, only those '96 and newer.
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Tuesday, December 29th, 2015 AT 5:22 PM
Tiny
BGOERMAR80
  • MEMBER
Yeah I'll try that for sure as of right now the truck sat for a month and I'm sorry if I wasn't specific enough I lol tell you what happened in full detail. Bacicly was driving and it just died in motion it's a manual. Pulled over and tried to turn it over and it cranked strong just wouldn't turn over. Popped the hood and took off the filter above the injectors that's when I saw the right enjector wasn't shooting out gas at all so I went and got 2 new injectors put them in and they worked but at this point I don't know if the engine was flooded or what long story short got it towed home in the morning I replaced the destributor and hooked everything up correctly and the truck started and ran good for the day but on my way to work going down the highway my truck started to loose power and before I knew it I look down at speedometer and it said I was going 45 I pulled off onto back roads and made it to work. After work we started it and I was looking and when I started it the motor was reving normal then to 200 rpm then high and back to 200 rpm and it did this over and over tried to drive it home and from a stopped position to moving it would jerk hard and almost die and jerk again and do this 3 times or more and would start to move regularly to a top speed of 35 to 45 mph I hope this helps I'm just in a hurry to fix it and I don't know much about tbi so I'm just trying to figure this out
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Tuesday, December 29th, 2015 AT 6:24 PM
Tiny
CARADIODOC
  • EXPERT
Along with all the things I already mentioned, you might want to connect a fuel pressure gauge and drive with that held under a wiper arm so you can watch what happens when the problem occurs. If the pressure drops significantly, consider the collapsing fuel strainer inside the gas tank, or, less likely, a failing fuel pump.

The scanner will let you view live data while driving so you can see what's changing. This is a place where you do not want to "cheap out", so to speak. A lot of the inexpensive readers for the newer cars only update their readings about once every three or four seconds. That is a lifetime of frustration when you're trying to find a momentary glitch.

Instead, look for a high-quality obsolete scanner. My Monitor 4000 cost over $700.00 new in the early '90s but today you can find them for around 50 bucks. You'll need to be sure it comes with the "Chrysler / Ford / GM cartridge for up to at least '93 models. This is very limited in what it can do compared to today's $10,000.00 scanners, but the cars back then were too. You are limited in what you can do too without a scanner to let you see what the Engine Computer is seeing and doing, just like a doctor would be lost without his stethoscope.
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Tuesday, December 29th, 2015 AT 6:44 PM

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