96 k1500 running lean

[Gr8dane98]

So I drove my 96 Chevy k1500 with the 350 vortec over a train track like any normal day and all of a sudden my truck is shaking real bad. I managed to get it to a friends garage nearby but I couldn't accelerate. It would only coast. It was running really lean and would fall flat on its face when i gave it gas. It had low fuel pressure so changed the fuel pump and fuel filter. It drives a lot better now but it still starts to fall flat when I try to accelerate too much. I still can't figure out why it won't accelerate.

So far I've replaced my...

Fuel pump

Fuel filter

Idle air control valve

Elbow tube on the pvc

Breather tube grommet

Spark plugs and wires

I put a new mass air flow sensor on it and that only made it drive worse.

What else could it be?

[chasebrew2010]

Do you notice a strong smell of gas when idling, or burning black smoke? Sorry, I know you said it was running lean, but mine was doing a very similar thing but it was running rich.

 

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[Gr8dane98]

When I first bought the truck back in November, I could smell gas back towards the gas tank but now I cant smell anything. I've been crawling under the truck for the past 4 days now and haven't smelled any gas. I checked the fuel pressure from the fuel pump to the fuel filter. the pressure was good but I haven't checked anything past that. The truck drives fine now that I have replaced the fuel pump and fuel filter but as soon as a try to really accelerate, it loses power and falls on its face. I put on a new mass air flow sensor which actually made it drive worse. What I think this means is that my old mass air flow sensor does need replaced but the lack of fuel is still to great to allow the new mass air flow sensor to improve the truck.

[chasebrew2010]

Have you took off the air filter, while running, and watched the injectors to make sure they are spraying properly?

 

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[Gr8dane98]

I haven't yet because of time and effort. I work 50 hour weeks and just haven't had time. I have thought of the injectors but another reason I haven't checked them is because I wouldn't expect driving over a railroad track would cause them to fail. it very well could be them but I haven't had time to check them or get them checked.

[chasebrew2010]

I understand that. Stupid work getting in the way of free time... if not that, the only other think I can think of is maybe the coolant temp sensor? I know you said it's running lean, but mine did the exact same thing when I would accelerate (it also gave me problems just idling) but the sensor was telling the computer to dump to much fuel in. I don't wanna insult you or anything, but the intake is clean huh? Like, no blockage or anything small like that ?

 

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[Gr8dane98]

It's clean as a whistle. I have considered changing the fuel pressure regulator, but I don't know much about them.

[Gr8dane98]

There Is a plug directly above the oil filter that is missing on my truck, do you know what plug that is?

[chasebrew2010]

The closest plug to mine is the O2 sensor coming out of the exhaust manifold. Can you follow the wired to anywhere?

 

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[barry G]

tracks are lit.

but these trucks are great at anti-reverse (like hooking jumper cables backwards- the truck will keep running)

 

I'd pour over gadgetry, if no codes.

map sensor is another gadget.

there is also a knock sensor.

 

 

I found after modernizing and fixing the ever lasting 96 vortec.. fuel for the 305 is 16mpg...and a lot more power than factory.

I'd keep going until mpg was 12-14 on the 350.

 

A common spot to get attacked backwards (ground up) the grounds in the back by tail lamps, licnese plate light, trailer wires, electric brake..

I had to scrap all of the oem setup for LED.

[1997SierraSLT]

If you are not getting the check engine light (which typically would indicate an injector misfire), then I'd suspect the MAP sensor. It is located on the upper plastic intake manifold next to the ignition coil. For some reason, the ECM does not set a code if this is faulty. I replaced mine and it ran like a bat out of hell afterwards.

 

Word to the wise, if you remove the MAP sensor, make sure you pull it straight up and out. Don't try and pry it out with a screwdriver as I did once. It broke off and fell down into the manifold. That was a nice six hour job.

 

Have you considered upgrading to the MFI fuel injection system. The CSFI fuel injection system caused a lot of heartache and misery as the poppet valves would clog up which would lead to a misfire condition.