I just got back from looking at a 97 GMC 3/4 ton extended cab 4*4 fully loaded pickup and was wondering what everbody thought of this truck. I was raised strictly in a ford family but this looks like a really nice truck.Would this truck handle a 20ft enclosed trailer all right,it has the 350 in it.I'm open to all comments thanks in advance,Bobby.
I've got the same truck in 2WD,i'm happy with it.Some people would rather have the 454,but this truck does just fine for me hauling 2 ztr's + all the other equip.

Anyone know what controls the fuel pump and injectors on a 90 blazer with a 350cid. i have no power to either one the pump is good. i cant find any relays or anything!!!!! please help
Have you checked for any codes? Maybe a wire is cut somewhere also. :confused:
normally codes wont show with truck not runing. the truck did run and then one day it stoped so i thought it was the fuel pump that was the only thing that has not been changed. so i did that tonite and when it still did not start i ck injector pulse and nothing..... :eek: and now its really starting to piss me off!!!! it should somewher have a relay or fuse but i cant find one yet.... what ever it is controls both at the same time i know that much.......... got anymore ideas :crying:
If I remember correctly.
The fuel pump is run off a relay, and low oil pressure will cut it out.
The injectors are fired off by the computer using the signal from the distributor (ignition module).
Did you check for spark?
The ignition module sets up the injector pulse and the signal to the ignition coil for spark.
If you have no fuel, no injector signal, and no spark then I would look for a fuse (ECM) or an ECM relay.
The pump should cycle with the check engine light for about 3 seconds when you turn the key to run, then stop.
It turns back on (the fuel pump) when it sees oil pressure (while cranking).
If you have spark then try pouring some gas into the throttle body (about 2 tablespoons) and crank the engine.
If it starts and stalls then you have a fuel delivery problem (fuel pump, Injector, filter, etc.)
If you don't have spark then you have a fuse, computer (ECM), relay, distributor, or (most likely) an ignition module failure.
Mebes is correct.
Also, I have had a similar problem with my own truck. The wire running from the fuse box area to the tank is going bad INSIDE the insulation and needs to be replaced. I keep patching it but proper replacement is the only solution...
the truck runs when you put gas it the TBI it has spark and oil psi i cant find a relay for the fuel pump anywhere . some keep telling me ign. module i will try that on tuesday..... and all the wiring is good i traced it . im thinking it and ECM :crying:
the truck runs when you put gas it the TBI it has spark and oil psi i cant find a relay for the fuel pump anywhere . some keep telling me ign. module i will try that on tuesday..... and all the wiring is good i traced it . im thinking it and ECM :crying:
Doesn't make sense to be an ignition module if it runs when you put gas down the TBI. Fuel wiring problem.
On my truck (the wiring was taken from an '87 R30 dually) the relay is one of two that are bolted to a small bracket on the passenger side of the firewall above the heater core (near the hoses that go to the engine and rad). They don't look like a standard small cube-style relay, they are longer (maybe 3"?), like a rectangular block with the corners cut off (ovalish-shape if looking from the top).
They are about $10 new from GM, I bought one for testing purposes. I put my old one back on because it still worked.
I assume you checked the ground between the fuel tank and the frame of the truck, right? Very Important!
If it runs when you pour the gas in then it's probably not the ignition module.
The ECM probably uses a different oil pressure sender than the one that sends to your gage on the dash.
Call the auto part store and find out if you truck has 1 or 2 senders for oil pressure.
Does the check engine light turn on for 3 seconds when you turn the key to run?
Do you have a tap on the fuel rail to check fuel pressure? (looks like a tire valve but smaller)
You said you checked the injector for injector pulse.
How did you do that? (what tool)
By the way I have installed fuel pumps before that were bad right out of the box.
Check for voltage at the connector at the fuel tank.
Or jump power to it (fuel pump) to see if it runs.
Maybe you have a bad ground back there.
I cked the injectors two ways one with a noid lite and two with a test lite no power as for the fuel psi valve there is non like that on TBI models. i cked ground and made a new ground no good. the pump is good i used a jumper and it runs, But with no pulse it will not run. i will ck the fire wall pass. side for the relays first thing in the a.m. thanks guys keep the ideas coming
Best thing to do is go to the parts store and look for the haynes book that covers the tbi. Looking at the book I have hear it should be book# 10220. See if that helps you.
Kinda long, but bear with it....
About 2 months back, I got a call from a guy to check out an '87 C-20 van. It had a 350 TBI. Probably just like the TBI on yours. I checked every last trace that I could. Did the noid light deal. After a week of trying to track it down, I sat down with the guy, and showed him the noid light test as a way to show him the reason why I was giving up. He was going to take it in. Plain and simple. I got injector pulse on both sides of the TBI when I showed him. I rehooked the injectors, and it ran. Until the end of the driveway. The tech that got it running for him said it was the main computer. It runs like a champ now. I hate to ruin your day, but that sounds like it's the problem for you too.
In a while, Chet.
I cked the injectors two ways one with a noid lite and two with a test lite no power as for the fuel psi valve there is non like that on TBI models. i cked ground and made a new ground no good. the pump is good i used a jumper and it runs, But with no pulse it will not run. i will ck the fire wall pass. side for the relays first thing in the a.m. thanks guys keep the ideas coming It's starting to sound like ECM relay, or bad computer to me.
Does the check engine light come on when you turn the key?
OK, thanks for all your guys help! :nod: i greatly appreciate it, after talking to the idiot i bought the truck from he said his tech. told him it was a fuel pump, no big deal whe i got it home i put a fuel pump in the truck and as you all know it didnt run. I cked everything you all helped with and then some :dizzy: , just to find out this guys TECH :angry: pulled out the ECMB fuse which controls the TBI and INJECTOR pulse. YEP A $.20 FUSE IS ALL IT WAS !!!! :guns: THANKS ANGAIN

I need to rebuild my 454 in my 1 ton 3+3 and would like it to have more low end pulling power. I went the other direction in the last rebuild. I am an old hot rodder at heart and built a 450+ hp monster that ran great over 3500 rpms, but would not pull worth a s---. Need a little help on building a mild mannered stump puller.
I have been considering the same for my '76 Suburban 454. The key is to look at low RPM operation. Start with a mild compression (maybe 8.5:1 or 9:1) rebuild, keep the valves in the heads stock, but you may want to have a mild pocket porting job to clean up the combustion chambers and make them more efficient. Use an Edelbrock Performer intake and the smallest tube size equal-length headers you can find. I am planning to use DynoMax CeramCoat, which are ceramic coated and run a little over $200 for the set. Use a cross-over pipe in the exhaust system as close to the engine as you can fit it. Keep the QJet, but have a high-quality rebuild done on it, including new throttle shaft bushings. The trick is the cam...I haven't picked on yet myself. Called Comp Cams, they recommend a Comp 256H, which is pretty mild but is supposed to be good for towing.
What transmission and rear end gears are in your truck?
Jeff
http://www.jeffsclassics.com
Jeff, just curious, what does the exhaust crossover do for you? i would presume that whatever benefit it carries would carry over to a 350 w/dual exhaust also, no?
Greg
'84,
An exhaust crossover helps low RPM power and also alleviates the droning of the exhaust at idle, however, at WOT the exhaust just whizzes past the crossover and out. Yes, any V-8 engine with dual exhaust will benifit from this addition. There are a few experts on cams over at the forum on http://www.454ss.com It is a real sience with cams, but all the work has been done these days. Just stay small. A big block can "eat" more cam duration and still be mild than what a smallblock can have.
I have a Turbo 400 with 4.10 gears....been trying to find someone who has put an Allison at545 in a Chevy truck, but no replies, I pull alot of weight, around 18k total. I eat a trans once a year.
crw432,
18K GCWR is a lot of weight, however, something is wrong with your cooling system for you to be smoking tranny's every year. Are you running in the mountains? You have the Texas heat to worry about, however, you have plenty of room for more tranny coolers. Try a remote located cooler with its own elec. fan. Keep the tranny fluid out of the regular radiator alltogether and run two aux coolers out front of the radiator and run the fan mounted one under your passenger seat (outside of course) right before the return line enters the tranny. Run a 180 deg stat. and a good radiator with an external engine oil cooler and a stewart high flow water pump. Good clutch style fan and shroud. You may want to think about a 4L80 swap to give you an overdrive and (very important for heat) a lock-up converter. They have kits for non computer applications (Jet). As long as you dont mash the go pedal with that 12,000 lbs in tow, the tranny should survive more than a year anyway.
Happy Towing
For low end power,stick with the round port heads,recantgular port heads are for hi RPM's,not good in a truck engine.If your going to swap in an Allison 545,and totally rebuild the motor-might I suugest you swap in the B5.9 Cummins turbo diesel,the 73-87 style Gm's accept that engine nicely,and a mild version will give 300-350 hp,and 700-900 ft lbs at the wheels.I bet you can find a used motor for 3-4K,now that will pull 18K like its nothing,and low end will never be a problem.If you pull; much the saving s on fuel will pay for the swap,you''ll likely get double-to triple the mileage pulling that you are now,and double empty.Just a thought,since I love the 73-87 style GM's,if i find a clean one,that's the engine thats going in,Ill even buy one with 150K on it,since its got at least that much left in it,maybe 3-400K more.There is a guy on the TDR that has an allison 545 behind his Cummins,he regularly tows over 20K with no problems.

I have a 1983 GMC 3/4 ton pickup w/a np 208 t-case. The problem I am having is the transfer case wont shift into 2wd. I can shift it into 4hi and 4low and neutral just fine. but if I try 2hi it sounds like it wants to engage but wont or will and pop right back out if I try to drive the truck. I have had it on a lift and tried to manually shift it without the lever in the cab attached and it still wont go into 2hi I can hear it click on the detent in the case. Any help would be appreciated. :( :( :(
It could be that a tooth is broke off one of the gears for the 2WD. That or a set of dogs are badly worn and they are not staying engaged.