I dont post alot because I really try to research before I post a question. I have a rebuilt 1990 7mgte with less than a 1000 miles. Mods: lex afm/ rc550/walbro gs315/aeromotive fpr. Issue: car was running great after rebuild but i blew the headgasket within 600 miles. took bad advice and used a copper gasket. took the head back off used cometic mls. now the car is hard to start and when it does its runs terrible when i push the accelerator it dumps so much gas into the engine until a puddle of gas is under the car. its coming out of the downpipe onto the garage floor. (exhaust is unhooked its on stands). There are no codes. I have checked everything that I know of. Grounds/temp sensor/new cps and wiring/injector resistor checks out/fuel pump relay checks out/timing is right/new coils,plugs,wires. What makes is dump fuel like that? its flooding the car. I have not checke the adjustable fuel pressure regulator because its only a year old. at this point I will try anything. Anybody please chime in with experience and advice. thanks
Help!!!!! I cant figure this overfuelling issue.
- Thread starter 7mboze
- Start date
Did you either
A- drill out the J tube, or
B- remove the J tube?
And what is your fuel pressure regulator set to?
A- drill out the J tube, or
B- remove the J tube?
And what is your fuel pressure regulator set to?
yes. the j tube is removed. the egr is removed. the fuel pressure is set as low as it can go the screw is almost out. the guage still reads 20 psi while cranking. thats with vacuum line connected. I also have the driftmotion upgraded ss return line.
Also, could be a stuck cold start injector.
Easy to test, just unplug it and try running it. Though I would only expect this to affect warm idle.
Easy to test, just unplug it and try running it. Though I would only expect this to affect warm idle.
I will check that. I will have to look at tsrm because I am not well versed in wiring. Other than the color scheme I am lost that will be a hard job but has to be done. Can please explain why crossed up wiring causes overfueling? I just want to know why. thanks for the response
If fuel is injected at the wrong time on the wrong cyclinder it will foul plugs and may go through to exhaust with out seeing ignition. If your not well versed in wiring I'm guessing you used plug n play connectors for your rc550 injectors if this is correct look at the factory harness connectors they should alternate in color if you remove the plug n play they should only reach the correct injectors. But if the harness has been modified by soldering in connectors for the rc550 injectors you will need the tewd for your year and options
Thank you for explaining that. I did solder new injector wire onto the factory harness to make the rc 550 fit. but i did that years ago the car has been running fine up until this last rebuild. But Either way thanks for your response and this week I will check them out.
So you put a cometic MHG on an undecked un-resurfaced block ?
If so, did you do a compression test yet?
Maybe it's the language barrier or a lack of intel on this issue, but to me it seems you have might a faulty head gasket if you just swapped the stock head gasket for a MLS gasket and only resurfaced the head and not the block.
If so, did you do a compression test yet?
Maybe it's the language barrier or a lack of intel on this issue, but to me it seems you have might a faulty head gasket if you just swapped the stock head gasket for a MLS gasket and only resurfaced the head and not the block.
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The engine was fully rebuilt and machined head and block by a guy who owns a rail and has his own machine shop. The engine was blueprinted and balanced internallly. the front cover was machined with the block. I also checked the rivets before putting the head on the block. the new cometic gaskets have fixed the rivet issue. Could you please explain what would have to do with overfueling? I am confused.
No i have not. I am not immune to simple mistakes as that. I label all electronic parts with tabs upon dissembly to prevent this. I will have to check again because I have tried everything else. I just check the TEWD. It was kind of confusing, It didnt have the injectors in order. This the color code that I got from the diagram, if I am wrong please correct before I start to work on my car in the next hour. The color code is inj.1.- white/blue inj.2- white/res inj. 3 -white inj. 4 white/blue inj.5-white inj. 6-white/red
7mboze;1902693 said:
What?
It's 1 and 4 colors are yellow and white with light blue stripe.
2 and 6 are black and white with red stripe.
3 and 5 are red and white.
Okay so a quick run down.
Car ran fine before you rebuilt it, now that it's rebuilt it's over fueling?
Over fueling brings a few things to mind, while your car was down being rebuilt, you got injectors stuck open.
It could also be your fuel pump voltage is too high or your base fuel pressure is too high. If you can't control or bring the base fuel pressure down you have a restriction in the return line, whether it's dirt in the line or whatever, something is holding up the flow, somewhere.
Car ran fine before you rebuilt it, now that it's rebuilt it's over fueling?
Over fueling brings a few things to mind, while your car was down being rebuilt, you got injectors stuck open.
It could also be your fuel pump voltage is too high or your base fuel pressure is too high. If you can't control or bring the base fuel pressure down you have a restriction in the return line, whether it's dirt in the line or whatever, something is holding up the flow, somewhere.
THanks for your response Indigo but we said the exact same thing a different way. I just gave the color of the second wire. I just thought it was understood about the yellow black white wires. sorry my fault on not being clear. 2. come to find out cylinder 5 and 6 injector wires were switched. 3. The injectors were sent off a month ago to rc engineering to be check and balance. they are fine. 4. I have an aeromotive adjustable fuel pressure regulator and I dont know if the diaphram is bad. I have been told that they will go out and overfuel but I am afraid if I take apart that I may have to buy a new one. Its only two years old. What are your thoughts? The base pressure is set is the 33 psi vacuum line on. but the pressure drops as soon as the car turns off. so just not sure on a ton of issues. I dont know if its cold start injector stuck open, fuel pressure regulator, or check valve in the walbro fuel pump or if the switch injector wiring will fix it. I put the clips back right have not had time to try to crank it. wife and kids are off all week with me. I hope you understand. thanks for the response and sorry for not being clear
IndigoMKII;1902708 said:
I doubt it would cause such severe issues, I had 3 injectors mixed up once and car still started fine. Only issue was it had really bad tip in, and a/f was not as stable.
hey after church today, I will get right on it and report back as soon as possible. although after the post I just got from jg5899 it does not sound to promising. jg5899 just said the he mixed up 3 injectors and his car started and ran fine. I only had two and mine wont rev up and runs like its on 3 cylinders. But I am a optimist I think it will fix it. if not on to the cold start injector or adjustable pressure regulator. With the help of you guys and persistence we will find the issue. Thanks you guys are great!!
first of all thanks for the response. But I really hope you are wrong about my issue lol... no disrespect though. I will let you know , although you maybe right I still think it is a major overfueling issue when injector 5 and 6 are switched. I atleast will have to look into it. Thanks.jg5899;1902813 said:
jg5899;1902813 said:
Not sure how this is possible, when an injector went bad on my friends supra, he had a hard time keeping it running..