1997 Tahoe will not start!


#1

My brother’s truck is a 1997 , 5.7 L gas engine, fuel injected.

100k+ miles.

New plugs, wires, new rotor, coolant temp sensor & air filter & recent battery.

Started a few times after the new air filter & some dry gas & fuel injector cleaner & that was the last time it started.

Turns over but will not run!

He needs this truck to tow a trailer to R/C boat shows (he makes parts for R/C racing boats)

Help!


#2

First narrow it down to fuel or spark.

  • Spray some starting fluid into the intake. If that gets it to fire, even if briefly then you need to troubleshoot fuel. Start with whether or not the fuel pump is running at all - you should be able to hear it hum when the key gets turned to the run position. Listen through the gas filler neck if you have to. If the pump runs you need to get a fuel pressure gauge on it.

  • Use a spare spark plug or a spark tester (from any auto parts store) to check for spark. If none then you need to troubleshoot ignition. Was it starting before the new plugs & wires? Did all of the spark plug wires go back to the right places?


#3

It would start occasionally…usually after you almost flooded it.

Spark plug wires in correct places.

It will start with enough starting fluid in the carb & run for a while (like until the fire from the starting fluid goes out).

Time for a fuel pump or something.

He’s missed so many R/C boat races this year it is not funny.

And his wife is not a happy camper either.


#4

You’ll have to clarify. If it is flooding then its probably not a fuel problem.

Yet you said it will run with a shot of starting fluid which suggests a fuel problem.

So maybe you want to clarify.

It may or may not be time for a fuel pump. First its time for a fuel pressure gauge.


#5

Okay, so…

What I was trying to say is this:

If you get enough starting fluid into the carb, it will start & run for a few minutes & then it dies.

If you combine the 1/2 can of starting fluid with lots of pumps on the gas pedal, it will start & run, for a while.

Once it is warned up, if you keep your fingers crossed, say lots of prayers & eat all your vegetables, it will run & re-start after it has sat for a couple of hours.

Does that help?


#6

I’m the brother mentioned in the opening note. My sister got it almost right, we didn’t try starting fluid because there appears to be plenty of gas flowing to the engine. You can hear the pump running in the fuel tank. The initial repairs included new plugs, wires, cap and rotor, after which it would start if you cranked it for 5 seconds or so, then waited about 15 seconds and cranked again. That would usually get it to start and, once started, it would continue to run. I drove it home from the garage where it was worked on, about 3 miles, with no problem. That episode cost me over $220.00 and the next time I tried it, back to square one. Wouldn’t start regardless of what combination I used. Next I replaced the coolant temperature sensor because a friend who works in the parts department of a local GM dealer was sure that would fix it. It didn’t make any change. Then we put in a new air cleaner. Ditto, no change. If we fiddle with it for a while, sometimes it will start and run, but the results are not repeatable over more than a few minutes span. Battery is good, and charged, posts clean. Battery cables are in good shape, clamps are clean and corrosion-free. Turns over well, not sluggish or hesitant.
What about Mass Air Flow sensor, another friend’s suggestion?
Any other ideas? I really need to get this vehicle up and running (and not just to tow my trailer to boat races) and don’t want to turn it over to the local GM dealer for fear it will cost me a LOT more than it already has.


#7

Hi brother! Thanks for correcting me.


#8

Hearing the fuel pump operate is one thing - but has the actual fuel pressure been checked? cncop mentioned the carb, but unless someone modded the truck it is fuel injected. I don’t know the specs or procedure for this engine but checking the pressure is normally not that complicated. Its probably supposed to be somewhere in the range of maybe 45psi - perhaps as high as 60psi.

If it frequently stinks of gasoline while you are cranking it then I’d worry about that less and instead pull the vacuum line from the fuel pressure regulator to look for signs of liquid gasoline. If you find liquid gas in the vac line, then you need a new regulator.

If the pressure is good & the regulator has no trouble make sure the injectors have power & are clicking.

Has spark been checked during any of these non-start episodes?

Whatever you don’t don’t continue to go on guesses (like coolant temp sensors or MAFs) - people can guess all day while you just keep oozing $$ from the wallet. Here’s another - GM crank sensors are often a problem. And another: your fuel filter is clogged. And another: you have a bad ignition coil. And anoth…