98 Blazer starting problems

Some days, my Blazer gives me trouble starting. usually only first thing in the morning.

Mechanic says it sounds like it's draining back, and I should cycle the key (my comment: like glow plugs for a diesel).

Sometimes that helps, and some times it takes eight or ten or more tries to start.

What might be wrong?

Reply to
Stormin Mormon
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Fuel pump issue?

Reply to
SteveF

FIRST of all, determine if it IS a fuel pressure drainback problem. Dead easy. take the cap off the schrader valve on the fuel rail and push in on the valve pin. If it sprays fuel it is NOT a drainback problem. If it doesn't, cycle once and recheck. If you have pressure now, start looking somewhere else for your problem.

Do you have spark on first crank?? - pull wire off of one plug and check. Spark bright blue and snapping? Look elsewhere. If not - check ignition. When were the plugs/wires last changed? Is this a distributor engine or a coil pack engine??

If you squirt half an ounch of gas down the intake, hold the throttle half open, and crank, does it start??? If so it is a fuel problem. Could be a bad engine temp or intake air temp sensor telling the computer the engine is warm when it is not.

Reply to
clare

My mechanic doesn't think it's fuel pump. When it starts, it runs with pretty much full power. He thinks when they go bad, the engine doesn't rev properly.

Reply to
Stormin Mormon

SM: I may try that.

SM: That's a team sport. My arms are too short.

When were the plugs/wires last changed?

SM: Don't know. I got the truck used.

Is this a

SM: Coil on passenger side, next to module. Right next to (what used to be called) carburetor. Distributor cap has four wires one side, three on the other side.

SM: When it refused to start the other day, ether didn't do it.

If so it is a fuel problem.

SM: You know, I'd not thought of that. Thank you.

Reply to
Stormin Mormon

If the check valve in the fuelpump goes bad, it will drain the lines making starting difficult, and will still run perfectly after it starts - with full power. Another thing that can cause pressure drain-back is a bad FPR (fuel pressure regulator) which lets the pressure bleed off through the return line. This will USUALLY show up as a slightly lower than normal running fuel pressure, but not always

- and usually not enough to be readilly noticeable. Clamping off the return line immediately after shutting off the engine can eliminate this as a cause. Also check the vac hose connected to the regulator - if there is gas in it with the engine just shut off, you have a bad FPR. If it looses pressure without clamping the line, and does not with the line clamped, the FPR is leaking.

Reply to
clare

If ether doesn't start it, it is NOT a fuel problem and not a temp sensor problem, most likely. How long have you owned it??? I'm betting on bad plugs/wires Won't start cold and damp - run's reasonably well after starting. Likely costing you extra fuel as well. With the engine running, run your bare hands over the plug wires. If you feel ANY shock, the wires need replacing - yesterday. Also make sure the coil tower and the cap are CLEAN. Would not hurt to replace cap and rotor while you are at it. The whole job will cost you about the equivalent of a tow - - - - -

Reply to
clare

Yesterday, I pulled a couple relays out of the fuse box, and put some dielectric grease on the prongs. Today, the truck started better, but not right up immediately. I'm going to give it a couple days and see if things are better.

I've had it for couple years, and not had a tune up. The power is low, and it's a bit sluggish. I'd dare to guess it needs cap, rotor, wires, plugs. That's going to wait a while till warmer weather, and more money.

Reply to
Stormin Mormon

Borrow his pressure gauge and check for yourself.:-)

Reply to
SteveF

Buy one at Harbor Freight with 25% coupon?

Yesterday, I pulled the relays out of the fuse box, greased the prongs with dielectric grease, and replaced. Truck starts some better, this morning.

Reply to
Stormin Mormon

Possibly. I do not know if they may be used for anything else. So, spend at your own risk. If you have access to one, borrow it.

You might want to wait for SteveW to chime in. I know others have mentioned testing the fuel rail via schrader valve. One thing is to find the fuse for the fuel pump and pull it while the engine is running. Let the engine run till it dies. Turn off the key, replace fuse, then depress the schrader valve. After you are assured that the pressure has been released, cycle the ignition on and off three times, leaving ignition on (not in starting position) for around 10 seconds each time. Depress the schrader valve again. There should be a pretty good hiss/ spray of atomised fuel coming out. Be careful, little flame thrower there. :-)

Wait until morning then cycle the ignition three times, again, then try starting the engine. Sometimes the engine may run fine while the pump is not putting out enough pressure, as Clare stated (I believe), but is a pain to start since the engine needs more fuel. That's why I recommend trying to find a pressure guage. Hell, drive to an Autozone and use one of theirs in the parking lot. I think 45PSI is the min, but I really could not say.

Reply to
SteveF

Since he obviously doesn't know how to use it.

Reply to
clare

How much warmer is it this morning?

Reply to
clare

Default

Fuel pressure and leakdown must be checked with the engine off. On

1998 and newer, in the underhood fuse panel there is a vacant terminal next to the fuel pump relay. This is the "fuel pump prime terminal" and it goes directly to the fuel pump. Connect a jumper wire from battery positive to the terminal. After the fuel pressure stabilizes, it must be 60psi to 66psi. Then remove the jumper wire and the fuel pressure must remain above 55psi for at least 10 minutes. If it fails either or both parts of the test, there is a problem with fuel delivery and further testing is required to pinpoint the problem. If it drops too fast, clamp off the return line when you shut off the pump and see if it drops more slowly. If so, you have a bad FPR. If not, you have a bad check valve in the pump (or a leaky fuel pressure line, or a leaking injector, or a leak somewhere else in the high pressure side of the system (like a leaky diaphragm in the FPR - which will show up as gasoline in the manifold vacuum sense hose on the FPR).

Stormy needs to learn how to diagnose. I've done it for a living for over 45 years and I'm pretty good at it.

Reply to
clare

It's not good manners to flame someone who isn't here, you've not met, and you don't really know his abilities.

Reply to
Stormin Mormon

About twenty degrees, F.

Reply to
Stormin Mormon

Stormy - if he knew how to use it he would be able to check it and tell you for certain if it is a fuel pressure problem. -or have you not been able to start the vehicle and take it in so he is just guessing? Regardless - you DO need to test it - follow the troubleshooting info I have given and get back to me.

Reply to
clare

Exactly - which may be why it starts better now. If you have a crystal of ice stuck in the check valve or the FPR it won't start very well. - among a lot of other variables. Start the process of elimination. Eliminate either what is working or what is not from your list, one at a time until the problem is nailed down.

2 years since the plugs have been changed? Start there - they will need changing anyway if you keep the vehicle - but check the cables for leakage first.
Reply to
clare

========================== > 2 years since the plugs have been changed? Start there - they will > need changing anyway if you keep the vehicle - but check the cables > for leakage first. >

You don't have the authority to give me orders.

Reply to
Stormin Mormon

Not orders, stormy - just suggestions. You want to fix the Blazer so it starts reliably. Your perogotive to learn from my experience or not. I can guarantee I could pin down where the problem is on that vehicle within 20 minutes of arriving on your doorstep, assuming the vehicle was available.

Reply to
clare

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