95' K1500 Flooding Out On Shut Off

jkingsland · June 7, 2008

Flooding after you shut it off.

Hello, I have a 1995 Chevy k1500 silverado z71. The problem was there before any of this was installed but the exhaust was already on it. This has all been done within the last month. New headers, full dual exhaust (no cat) with glasspacks(being removed tomorrow). All brand new parts. O2 sensor(moved from right of truck to left side) map sensor,tps,iac,cts,rebuilt throttle body(oldinjectors still) plugs ngk, egr valve, fuel filter, wires msd, msd coil, msd cap rotor, full msd offroad ignition, cold air intake, intake gaskets,valve cover gaskets, throttle body spacer. Before I installed all of this listed, but 2 days after I installed the exhaust upon shutting it off I could start it right up, but if I let it sit for more than 5mins it was flooded out with gas, now after intalling everything else When I drive it, it also boggs down then does good then boggs again. I am a ase cert tech myself but this is becomming a nightmare to me. The only things I have not replaced yet are the knock sensor, timing chain, fuel injectors or the fuel pump. It almost seems like bleed down to me. If I try and start it as soon as I turn it off it will start fine, but if I wait more then 5mins it smells like raw gas in my exhaust and the plugs are wet, I have to give it gas(gas peddel) to start it. Also when it sits there at idle it almost seems like it has a missfire, but might have to do with the fuel issue. Any help would be great!! thanks

jkingsland · June 8, 2008

update:

today I put the scan tool on it, truck has a code 33, map sensor to high. Im going to do some testing on it tomorrow. If its the map sensor i'll just replace it again. I'm also going to remove the intake and see if I have fuel bleeding out of the injectors once I shut the truck off. Oh yeah, the bogging down driving down the street has nothing to do with running condition, the owner just needed to put gas in it. run still runs rough at idle, but runs fine driving. also has fuel beeling off after ignition is turned off, I believe.

copenhagen · June 9, 2008

Well for the ideling problem, check the EGR to see if its sticking.

jkingsland · June 9, 2008

Thanks for the reply, I just installed a brand new napa egr and it is not sticking. I also cleaned out the egr tube/ports.

Forgot to mention I also installed a brand new accel heavy duty ignition module as well.

Magnumb · June 9, 2008

Try looking into your fuel pressure regulator (could have a tear in the bladder). What is your engine timed at?

jkingsland · June 9, 2008

Try looking into your fuel pressure regulator (could have a tear in the bladder). What is your engine timed at?

I just rebuilt the tbi again on friday, with a new regulator diaphigm. It was leaking but it didnt change anything. I also tried another Map sensor and it made no difference. I still have to check the timing as it was set dead on before this problem, however I just installed a msd offroad box and need to check it again now.

redvett · June 9, 2008

You better look at your scanner and fine out what data isn't correct, you have probably changed a lot of parts that have no correlation with the problem.

jkingsland · June 10, 2008

You better look at your scanner and fine out what data isn't correct, you have probably changed a lot of parts that have no correlation with the problem.

I noticed while driving that the map sensor is reading over 4 volts im going to go over the flow charts tomorrow and see what the parramiters are. All of the items I replaced where junk ecept for the ignition module, I replaced it to keep up with the msd system. The truck is running very very rich, after 30 mins of installing the brand new ngk u-groove plugs, they where covered in carbon. Smell like raw fuel in my exhaust. When it sits there at idle its not backfiring but it does pop every now and then from the exhaust. Sounds like my baja boat running.

I have already traced wires and all are good and grounds are good. Map sensor sets off the check engine light with code 33 voltage too high, but only when driving in city traffic for more then 5-10 mins, if I get right onto the highway and do at least 60mph it will not set the code untill I get off the highway/interstate and drive in city traffic.

If anybody is wondering why I am running ngk platnum plugs in a 95' chevy truck, i am only running them because they are ok to use with the msd system. otherwise I would be running normal ac delco plugs.

Today I took a know good spare map sensor and tried it, no difference, however if you disconnect the vacuum and plug it off and leave the map sensor pluged into the elec connector it does run better. But still runs very rich.

jkingsland · June 10, 2008

I need to get the glasspack mufflers off of the truck and see if that does anything giving it more backpressure. I have brand new flowmasters for it.

copenhagen · June 10, 2008

Your problem sounds exactly the problem i had with a friends, and hear what we did...didnt fix it tho, one day we started it after sitting a week and it ran perfect

New battery, sometimes if the battery is crappy it wont run good

coil/plugs/wire/cap-rotor/module

EGR

MAF

coolant temp sensor

timming

If you lift your coil wire about 2cm from the coil it will run smooth i bet,, it gives a stronger spark.

Maybe get out your DMM and check the voltage on your injectors, your going to have to backprobe the connector with a pin...if their too much current for some reason then it will over fuel

jkingsland · June 14, 2008

Just checked it out yesterday, did something I should have done to start with. Pulled off the cold air intake to watch the fuel injectors, sure enough, The injectors are bad. I also expect the brand new map senor to be bad also because if you disconnect it, the truck runs the same. But I will have to check that after I put the new throttle body on it. As it might run still because of it just dumping gas.

GMTRUCKTECH · June 17, 2008

AFTERMARKET parts suck azz!

jkingsland · June 28, 2008

Well, Injectors bad, and computer bad. Thanks to all that helped but the TBI system is going into the trash can. I have bought an entire TPI system for my truck this is great news it is a much more relieable system. But now the fun part, how to wire up my 4l60e? transmission to the tpi computer.

Shoestringmechanic · June 28, 2008

Well, Injectors bad, and computer bad. Thanks to all that helped but the TBI system is going into the trash can. I have bought an entire TPI system for my truck this is great news it is a much more relieable system. But now the fun part, how to wire up my 4l60e? transmission to the tpi computer.

50/50 my hubby had just said the same thing that one other reader had about your truck, as I was reading it to him. He thinks that you don't have enough back pressure and your sensors in the exhaust are not reading correctly. He said put converter back on and the flowmaster behind it. He's always done that, he likes a lot of racket also.