1990 No Up Hill Power?

[LynnJr]

I have a 90 350 tbi 5 speed 4x4 that doesn't have any error codes in it.When I go up a hill blue haired old ladies pass me up.It cuts out like its starving for fuel or fouling out atleast 2 plugs.Once I get over the hill it runs much better but still doesn't like anything with some throttle in it before it starts cutting out.
I replaced the entire fuel pump assembly and measured at the filter running it looks like 10 psi.
I replaced both injectors and the filter.
I removed the catalytic converter and am running a test pipe.
Most of the small parts on the exterior have been replaced atleast once.
I replaced the computer but not the circuit chip that goes on it.
I am starting to think it is electrical.
I am the original owner and the motor is a newer crate motor from GM with probably 20,000 miles on it.
Any help or ideas are appreciated.
Lynn

[speedygonzales]

What is the history behind the problem? Are you able to check the pressure while driving it under similar conditions?

[LynnJr]

Speedy
I read a ton of posts here and decided to try the easy ones first.
I bought a Mr Gasket fuel pressure guage and 6 feet of rubber fuel hose.I tee'd it in were the fuel filter sits on the frame and ran th hose through the window with the guage and drove the truck.Nothing below around 9.5 pounds.

When I first start it in the morning it runs great through first and second gear but when I get it up to freeway speed in maybe 2 minutes it will start to spit and and sputter around 65 mph.

Around town it drives well enough but any driving were you need some throttle and you can't count on it running right.
Lynn

[speedygonzales]

Did the replacement engine ever run good was also what I was asking and if so, what was some info regarding when it changed?

Do you still have a functioning EGR and have you ever tried pulling and capping the vac line to it?

What about the distributor? Was it the original that was put in the replacement engine? If so what about the condition of it's components? What about initial timing?

You mentioned small parts on the outside. Did that include plugs wires cap and rotor?

[LynnJr]

SpeedyGonzales
The truck has almost 600,000 miles on it but the newest engine only has around 20,000 miles on it.

I was running it as a carburetor motor when it first went in and it ran great.When I put the factory tbi manifold on it ran good for 6 months and now its acting up.

I capped off the EGR lines and the vent and the only change I noticed was it through an error message so I unplugged everything and ran some sea foam through it.

I replaced the entire distributor with a pep boys unit.I don't think its very good quality.

The engine timing is zero degrees but it feels like it is really holding back on me.If I put my foot in it it feels like its down two cylinders and as the rpm comes up it starts to clear up a little bit but it never fully recovers.

Most every piece on the engine has been replaced atleast once and some items several times but everything is Kragens or Pep Boys items.

When I took it in to get the test pipe made the guy at the muffler shop who drove it on the rack said it sounded like a dead cylinder to him.
Lynn

[Boog]

Burned valve possibly? A compression test might be in order.

[LynnJr]

Boog
You and I think alike.
When I bought this motor from my local chevy dealer and installed it I had a low end miss.I ran a compression test on the drivers side and one cylinder was dead out of the crate.I took it apart and it was a valve seat problem.
I can't for the life of me remember if both heads were done are just one.I will do a compression test on sunday and report back.
Lynn

[LynnJr]

I just checked the compression and all cylinders run 125-135 pounds.
I will put another cap rotor and wires on it.These are new but I read on another forum much of this stuff is cheap copies so I'll see if that helps.
Anybody got anything let me know.
Lynn

[TennesseeZ]

You're testing FP ahead of the filter on the frame? Can you check the pressure at the TBI? You can get the fitting off Ebay. Have you visually checked the spray pattern/volume at the injectors? I'm thinking maybe some kind of low fuel delivery problem, can't remember if the TBI has an internal filter. How does it act in neutral working the throttle by hand? Just throwing this out trying to see if you've overlooked anything, the 2 times I've had symptoms like you describe it was a clogged fuel filter or cat.




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[LynnJr]

I tested the fuel pressure without the filter at all.I am running a non-factory filter on the frame and soft lines at the throttle body as I sometimes use a carb.
I can easily tee in at the throttle body and will see what I get.

I checked the spray pattern today after I tested compression and all looked well.

If I throttle it up by hand it runs good as well.

On flat ground it runs decent up to 60 mph
On uphill grades walking is better
On downhill grades it hauls the bacon.

No cat on the motor.
When its cold in the morning on my way to work it will pop at 65 mph.After it is warmed up it stumbles but doesn't pop anymore.
It really feels like a bad cap or wires but they have been replaced three times now without any improvement.
I can install a manifold and carburetor after new years to help isolate the problem if that is needed.
Lynn

[speedygonzales]

I'm not sure it's an engine problem. Maybe it's transmission. What's ever been done to it?

[LynnJr]

Speedy
The tranny is a 5 speed.
Lynn

[Richardwa]

My 92 acted similar to this, ended up being the fuel pressure regulator

[LynnJr]

How do I check it and were is it located? Is it internal to the tbi?
Lynn

[TennesseeZ]

Originally Posted by LynnJr

How do I check it and were is it located? Is it internal to the tbi?
Lynn

Here ya go, not a great image but it should do, 10,11,12 is the regulator. The spring breaks sometimes.

[speedygonzales]

You kind of checked it already when you used the fuel pressure gauge. One last check will verify it's ok. Hook it up and see how fast the fuel pressure drops when the engine is shut off. If it drops fast it can be the cause of the problem. But so can 2 other things.

However since you already replaced the injectors and the fuel pump, it's likely if the pressure drops quickly after shut down, the FPR is the cause of the problem.

But back to the tranny. My question was What's ever been done to it? Or since the engine is 20K old, do I assume you put a new clutch, pressure plate and throwout bearing in it?

[LynnJr]

I will replace the FPR today and report back.

The transmission is my 3rd in this truck.It was pulled from a 95 and I had to use the newer shifter as well.
When I put the new engine in I replaced everything but the flywheel which was re-ground.Its not slipping on up hill driving the engine is cutting out big time.If I lift off of the throttle it gets a little bit better.
Lynn

[TennesseeZ]

I think I remember reading ChevyTech posting that the spring is not available by itself. He said he gets his from the junkyard. There are vendors on ebay who sell springs designed to change the pressure, not sure you can get stock there. Pretty sure they don't come in the rebuild kit from the local parts house.

[LynnJr]

http://www.ebay.com/itm/GM-TBI-Fuel-...item3cc065ede1

Will this work?
Lynn

[Richardwa]

Originally Posted by LynnJr

http://www.ebay.com/itm/GM-TBI-Fuel-...item3cc065ede1

Will this work?
Lynn

That looks like the kit I got

[Richardwa]

Originally Posted by TennesseeZ

I think I remember reading ChevyTech posting that the spring is not available by itself. He said he gets his from the junkyard. There are vendors on ebay who sell springs designed to change the pressure, not sure you can get stock there. Pretty sure they don't come in the rebuild kit from the local parts house.

I got a rebuild kit for my regulator from the local parts house, it had all the parts. Cost about $60.00.

Here's a pic of what my old one looked like:

[speedygonzales]

http://www.chevyhiperformance.com/te...l/viewall.html

[LynnJr]

Finally got the kit but its now 7PM and dark outside BWD-21732p and it has the spring.
Now for a completely wild question!!!!!!
I am running rubber hose to both side of the TBI.No hard lines.
Is it possible they are backwards or does it matter?
Right now it has brass nipples on the TBI with 12 inches of rubber hose then back to the hard lines.
I will install the parts on sunday and its a quick job to reverse the hoses as well.
I was told the fuel in side is thicker so could the brass nipples be too restricting?
Also I was told the fuel in is on the right side.Is the right side driver side or passenger side?
Lynn

[Richardwa]

fuel inlet on mine is on the rear, drivers side of the TBI. Fuel line comes up near the back of drivers side valve cover.

Right usually refers to passenger side of vehicle, left drivers side

[LynnJr]

Put in the new FPR and it didn't change anything.New spring is shorter but just as stiff.A tiny bit of rust on the diaphragm but the old spring looked real good.

I swapped the fuel inlet and return hoses and that doesn't do anything at all either.The tbi looks like a holding tank for fuel and the inlet and out are interchangeable atleast if your using rubber hoses instead of hard lines.

Any other ideas or should I go with a manifold,carb and points type distributor see if that fixes it?
Lynn