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90 Suburban 454 running rich at startup.

My 90 Suburban R2500, 2wd, 454 cid, has a hard start problem. After she turns over for approximately 10-15 seconds, she backfires and begins running. There is a strong smell of gas after she starts, but once I get her on the road she runs and idles without problems ... other than very poor fuel economy.

I am suspecting the fuel pressure regulator and/or the relay. I am not sure if this is true, but to test the regulator I need to remove the vaccum line and rev the engine to see if fuel spills from the line. Is this correct? Where on the engine is the regulator located? The relay I am familiar with and it seems to be clicking on and off when the engine primes itself, so I am doubtful if that's the problem.

If anyone has any other ideas, please chime in!

Thanks, Andrew

Reply to
Andrew Ross
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TBI ?

then it is internal to the TB

Reply to
TranSurgeon

Yes, that's correct, it is throttle body injection. When you say "internal", can I reach it without any special tools? Where on the throttle body is it located? Do you think this is the problem?

Thanks, Andrew

Reply to
Andrew Ross

it is internal

I've never disassembled one

Reply to
TranSurgeon

Anyone know how big a job this is and if I can do it myself? Do the symptoms I described sound like this might be the problem?

Thanks, Andrew

Reply to
Andrew Ross

Ok, just an update. I tried to pull codes but nothing is showing. As far as the computer is concerned, everything is normal.

Andrew

Reply to
Andrew Ross

I suspect you have the same problem that I do. As the injectors get older they start to leak. So once you shut off the truck the fuel system depressurizes itself by leaking out the injectors into the intake. So in fact the truck is flooding. You can get a kit to rebuild the TBI unit and replace the two injectors but it probably will be as expensive just to get a rebuilt one from an autoparts house. Anyway, you can get to the pressure regulator easily (on top of the TBI) and if you get a rebuild kit make sure it does come with the regulator diaphragm (some do some don't, make sure you get the one that does). Just rebuild it and use the old injectors and see how you make out. If it still does it then replace the injectors. Make sure you do remove the TBI before you pull any screws and rebuild it on the bench...

Good luck, mark

Reply to
r_d

Thanks for the information.

If I give it to a shop, do you think they will be able to diagnose the problem, even if the TBI needs rebuilt?

Thanks, Andrew

Reply to
Andrew Ross

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