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...Throttlebody question...

Posted: Tue Aug 28, 2012 6:58 pm
by legends of the lower mars
I went down to LA to move my RV to higher ground and the sumbeach wouldn't start... Ended up towing it up the road bout' 10 miles to higher ground behind the flood protection levee.
Type of engine is a 1990 350 5.7
I changed fuel pump and filter and I am getting fuel all the way up to the throttlebody. I cracked open the fuel input line. I also pulled the top of the throttle body apart and there is fuel inside it. It's not spraying fuel though... It will start if you squirt a little gas down the throat. I'm pizzed to the max!

Please help!
Thanks in advance!!! :wink:

Re: ...Throttlebody question...

Posted: Tue Aug 28, 2012 7:04 pm
by huntsober
Mass airflow sensor?

Re: ...Throttlebody question...

Posted: Tue Aug 28, 2012 7:26 pm
by legends of the lower mars
huntsober wrote:Mass airflow sensor?
Please explain how that effects the opening of the injectors and how I will know if it's a bad sensor? I'm not a car mechanic, I'm a helicopter mechanic... LOL! :lol:

Re: ...Throttlebody question...

Posted: Tue Aug 28, 2012 8:24 pm
by huntsober
Im not either but it sounds like what mine did. When the MAFS goes out the computer does not read the air being sent into the throttebody. It acts like its not getting gas when your cranking it....It trys but it fires and goes dead. THe MAFS is a very sensitive sensor. It will be located before the throtte body after the air fiter. look for a set of two or 3 wires going to a plug in the air duct. Mine is a flat metal plate with a round hole for the air to pass. It has a thin wire across the hole. This wire reads the air flow. DONT TOUCH the wire, or spray carb cleaner directy on it. Its sensitive, Disconnect the battery wait ten minutes and reconnect. Sometimes this will resent the codes if any are out. It might fire up if the PC is reset. Again Im not a mech. but thats my 2 cents.

Re: ...Throttlebody question...

Posted: Tue Aug 28, 2012 8:30 pm
by TrevorH454
huntsober wrote:Mass airflow sensor?
No MAF on the old TBI's. Didn't have them until the 96 Vortec's. If you have fuel into the injector pods, especially near the front of the pod between the injectors, I'd suspect the injectors themselves aren't firing. The wiring to the injectors can get old and brittle (being 22 years old now), and injectors can go bad, but I doubt either is the case, since there are 2 injectors and the chances of both dying are slim. So, I'd lean more towards the ECM (computer behind the glovebox) not telling the injectors to fire. Disconnecting the battery for a bit to reset it would probably be worth a try.

Re: ...Throttlebody question...

Posted: Tue Aug 28, 2012 8:41 pm
by 99beers
Not sure on your deal, but I pulled the throttle body on my wife's blazer, gave it a good cleaning, and bam, no more stumbles or dying out

They get gummed up.

Re: ...Throttlebody question...

Posted: Wed Aug 29, 2012 5:07 am
by Sprangletop1
Agree with the last two post, how old is the gas and when was it last cranked? If you are testing wires remember, the ecm controls "ground" to tell the injectors what to do.