88 ragtop - Team Camaro Tech
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post #1 of 14 (permalink) Old Mar 30th, 09, 04:17 PM Thread Starter
 
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88 ragtop

i have an 1988 camaro rs convert with a 305 thtottle body injection, i'm having a fuel problem , I instaled a new fuel pump ,filter and now the car idle's ok but studders and stalls under load. At idle i have a good cone of fuel but when i throttle to a high reve i can see the fuel cone weaken , the check engine light is on , i ran the codes and came up with, 15,22,23and 34 I replaced all the sensors but it's still unable to run under load and suggestions or ideas what the problem could be,im going out of my mind it ran well about nov dec. my son was driving it to school the he said it was hesitating at lights ,stops ect. any help would be appreciated
thanks

ps .the cat can't be clogged , it dosn't have one
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post #2 of 14 (permalink) Old Mar 31st, 09, 03:33 AM Thread Starter
 
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Re: 88 ragtop

stalls under load
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post #3 of 14 (permalink) Old Mar 31st, 09, 03:35 AM Thread Starter
 
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Re: 88 ragtop stalls under driving load

[quote=88 ragtop;1188802]i have an 1988 camaro rs convert with a 305 thtottle body injection, i'm having a fuel problem , I instaled a new fuel pump ,filter and now the car idle's ok but studders and stalls under load. At idle i have a good cone of fuel but when i throttle to a high reve i can see the fuel cone weaken , the check engine light is on , i ran the codes and came up with, 15,22,23and 34 I replaced all the sensors but it's still unable to run under load and suggestions or ideas what the problem could be,im going out of my mind it ran well about nov dec. my son was driving it to school the he said it was hesitating at lights ,stops ect. any help would be appreciated
thanks

ps .the cat can't be clogged , it dosn't have one[quote]
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post #4 of 14 (permalink) Old Mar 31st, 09, 03:58 AM
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Re: 88 ragtop

How does the wiring to your TPS (throttle position sensor) look? The voltage to the TPS is very, very low, and it's easy to have a damaged wire reduce the TPS voltage and cause what you are describing. I had an 87 Chevy Truck with the 350 TBI, and it would act much like you describe, and it turned out to be a broken wire (or two, it has been a long time since that truck) on the TPS lead right at the TB. GM makes a "repair" TPS pigtail that includes the plug and 12 inches or so of each wire.

I think this is the one I got to fix my truck: GM PART # 12102568
CATEGORY: Fuel Injector
PACK QTY: 1
CORE CHARGE: $0.00
GM LIST: $36.94
OUR PRICE: $19.21


DESCRIPTION: CONNECTOR

Or, like this one from RockAuto (the picture for this piece looks like what I recall): http://www.rockauto.com/catalog/x,ca...,parttype,2624

Some good TPS diagnostic info in here: http://www.wellsmfgcorp.com/pdf/Counterpoint2_1.pdf

As far as the other non-TPS related codes, I would check those wires and connectors as well. Some coolant sensor diagnostic here: http://www.wellsmfgcorp.com/pdf/Counterpoint2_2.pdf


I assume you have a manual or other info that tells you what each of the listed DTCs mean, but I'll throw them here just in case they job another member's memory or knowledge base.

15 Coolant temperature sensor signal indicates a temperature colder than -38� F for 3 seconds.
22 TPS voltage was under 0.2 volts for 2 seconds when the engine was running.
23 Manifold air temperature sensor signal showed an air temperature below -22� F after the engine has been running for 5 minutes.
34 MAF sensor indicated an air flow of 25 gm/sec or less for 1 second when TPS was above 6% and engine speed was above 2300 RPM.

Eric
69 'vert project big block/TKO 600 RR
68 'vert driver RS clone -- gone!
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post #5 of 14 (permalink) Old Mar 31st, 09, 04:27 AM Thread Starter
 
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Re: 88 ragtop

the tps plug looked ok at the sensor, and i had the sensor(tps) tested , it was fine. i'll run the wires back as far as i can to see ,thanks for the tip i'll give it a try
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post #6 of 14 (permalink) Old Mar 31st, 09, 05:25 AM
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Re: 88 ragtop

can you tell us were the codes there before the pump replacement?? and why did you replace the pump?? was fuerl pressure less than 9lbs?...i don't want to send you in circles to fix something that may be a simple thng...
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post #7 of 14 (permalink) Old Mar 31st, 09, 10:04 AM Thread Starter
 
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Re: 88 ragtop

Quote:
Originally Posted by 67conv.cam View Post
can you tell us were the codes there before the pump replacement?? and why did you replace the pump?? was fuerl pressure less than 9lbs?...i don't want to send you in circles to fix something that may be a simple thng...

well the code for engine temp and MAT were there for a while but the car was sitting becouse i needed a radiator, I replaced the radiator and the MATsensor,the MAF sensor. The fule pump was replaced by my brother about 1 1/2 years ago, the car ran good until my son took it to school a few times and he stated it was getting worse with the hesitation and stuttering. The weather is getting warmer so i just started working on it again
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post #8 of 14 (permalink) Old Mar 31st, 09, 05:32 PM
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Re: 88 ragtop

I'd be wondering about ground connections and power to the ECM. Keep in mind that if the ignition was ever turned on with those sensors disconnected or a major ground lifted, you'd see weird codes like that amoung multiple sensors. That's too much of a coinsidence IMHO to be a single sensor failing or having a bad connection itself.

Whatever you do, avoid spending your hard earned cash shotgunning it with parts. Also, consider the fact that the codes you saw were a coinsidence stemming from previous work on the motor. Their could be other factors at play messing with your mind so don't overlook the fundamentals.

Give the distributor a good look over. Make sure there isn't carbon tracking in the cap between the electrodes. Make sure the center button looks good. Examine the pickup coil for corrosion and the magnet closely for cracks.

Make sure the vacuum lines are connected properly. If you're lucky, you still have an emissions sticker under the hood that will tell you how to route the hoses.

It would be interesting to know what your timing is doing when it begins to buck and fart.

Search the electrical forum for "voltage drop" in quotes. You should find a dozen or more posts explaining how to verify your grounds and power circuits are good. In summary you look for near zero voltage drops between major points in the ground system, and repeating the process for power. Just make sure the system is powered up (engine running in your case) while you take measurements. Do a wiggle test while observing the meter.

The gremlin is just laying there waiting to be found.

Dave
========================
68 Coupe, 350 w/ Edelbrock Performer RPM heads, cam, intake, 700R4, Dave's small body HEI
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post #9 of 14 (permalink) Old Apr 1st, 09, 08:35 AM Thread Starter
 
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Re: 88 ragtop

thanks Dave,
I did take the cap rotor wires ect. off inspect ,clean and found a sandy greenish/white buildup around the saft and the electrical component on the side of the distridutor was dirty and the 2 wires inside the cap corroded and the plastic plug cover broken, i cleaned it and reinstalled everything but now the motor turns but no fuel to yhe injectors, thereis fuel in the tank ,the pump runs , i can hear it but no fuel is comming out of the injectors, and ideas
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post #10 of 14 (permalink) Old Apr 1st, 09, 04:25 PM
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Re: 88 ragtop

Pull the dist install new pick up coil amd module cap and rotor. the sitting and damp caused rot.
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post #11 of 14 (permalink) Old Apr 1st, 09, 07:20 PM
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Re: 88 ragtop

The ECM may not (probably doesn't) command the fuel pump to run if it doesn't see ignition pulses coming from the distributor. Most ECMs work that way. You may hear the pump run for a second when you first turn the key, but after that, no fuel pressure until the distributor pulses came back. Maybe you were really close to the problem and disturbed a flaky connection. Do you have a timing light? Clip in on #1 plug wire and see if it flashes. If not, focus on the ignition and not the fuel system.

Dave
========================
68 Coupe, 350 w/ Edelbrock Performer RPM heads, cam, intake, 700R4, Dave's small body HEI
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post #12 of 14 (permalink) Old Apr 2nd, 09, 04:43 AM Thread Starter
 
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Re: 88 ragtop

Quote:
Originally Posted by dnult View Post
The ECM may not (probably doesn't) command the fuel pump to run if it doesn't see ignition pulses coming from the distributor. Most ECMs work that way. You may hear the pump run for a second when you first turn the key, but after that, no fuel pressure until the distributor pulses came back. Maybe you were really close to the problem and disturbed a flaky connection. Do you have a timing light? Clip in on #1 plug wire and see if it flashes. If not, focus on the ignition and not the fuel system.
thanks again Dave I'll try it , I dont like the computer cars bring back the 70"s cars ,I know how to play with them
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post #13 of 14 (permalink) Old Apr 2nd, 09, 04:44 AM Thread Starter
 
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Re: 88 ragtop

Thanks again Dave,
I'll try it and get back to you
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post #14 of 14 (permalink) Old Apr 3rd, 09, 11:02 AM Thread Starter
 
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Re: 88 ragtop

well i couldnt check the ignition with my timing light , its no workinh as well but i did run the codes again and now i only get code 15,colant temp.sensor, so i tryed to start the car and it started , little ruff idle but it idles but now i still have the original problem , bogging down with a load. i did notic that when i first started it i could rev it up as high as i could without bogging but once it was warming up it seemed to go back to bogging/stalling at i rev or under load. I'm still working on a timing light ,but at least its running now
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