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Vortec 350 no power/hesitation

Landon730

Landon730

Active Member
Messages
322
Reaction score
186
Location
Greenwood Arkansas
Here recently my 98 has been acting up once again. It started out as just a little miss at full throttle and now it’s turned into no power at all. It will run fine at idle and idle up perfect in neutral. If you put it in gear and try to drive it, it instantly loses all power and hogs down. Camshaft PS has been changed plugs wires cap and rotor have all been changed recently. I tested the TPS and it tested good. Ohmed out all of the o2 sensors and they tested good. Cats aren’t stopped up. MAF sensor has been cleaned at least 4 times. It was making the manifolds glow red when I pulled a trailer with it the other day when it started acting up. I have a picture of the manifolds
 
Put a fuel pressure gauge on it. This sounds like classic poppet injector failure. They need at least 55 psi to properly open, anything less, and it stumbles and pops. Make sure abd check it under load. The multec2 replacement injectors in the upgrade kit do not have this problem.
 
THEFERMANATOR said:
Put a fuel pressure gauge on it. This sounds like classic poppet injector failure. They need at least 55 psi to properly open, anything less, and it stumbles and pops. Make sure abd check it under load. The multec2 replacement injectors in the upgrade kit do not have this problem.
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I was thinking about taking the upper intake off to look at them. I’ve been planning on getting the upgrade for awhile. Could it be the ecm by any chance? I can go to the scrap yard and get one cheap. I just don’t have a fuel pressure gauge so the only way is to physically look at them. Come to think of it, for awhile it has been making really short hiccups. You’ll be driving down the road and just kinda cut out for 0.2 seconds or something. It’s extremely short. It’s done this for a few thousand miles. Could this also point to injectors?
 
THEFERMANATOR said:
Put a fuel pressure gauge on it. This sounds like classic poppet injector failure. They need at least 55 psi to properly open, anything less, and it stumbles and pops. Make sure abd check it under load. The multec2 replacement injectors in the upgrade kit do not have this problem.
Click to expand...
Found one for $20 at harbor freight I’ll go get tonight. If the fuel pressure is normal, are the injectors the problem? Fuel pump was changed in January
 
New parts don't mean good parts. ALL of your problems point to low fuel pressure. If you don't have 55-56 psi of fuel pressure, it will NOT start, just spin over free as can be. The hiccups going down the road is also indicative of low fuel pressure dropping below 52(it needs 55 to start, but can idle and run at low loads on 52, under power it needs 58). Pulling the intake will tell you nothing. The common failure with poppet injectors is leaking pressure after shutting the engine off and poor idle from fuel leaking past the poppets. The poppet design is BEYOND picky when it comes to fuel pressure. As to the PCM, I doubt thats your issue.
 
Landon730 said:
Here recently my 98 has been acting up once again. It started out as just a little miss at full throttle and now it’s turned into no power at all. It will run fine at idle and idle up perfect in neutral. If you put it in gear and try to drive it, it instantly loses all power and hogs down. Camshaft PS has been changed plugs wires cap and rotor have all been changed recently. I tested the TPS and it tested good. Ohmed out all of the o2 sensors and they tested good. Cats aren’t stopped up. MAF sensor has been cleaned at least 4 times. It was making the manifolds glow red when I pulled a trailer with it the other day when it started acting up. I have a picture of the manifolds
Click to expand...
My friend it sounds like your torque converter went out in your transmission
 
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