91 Bravda won't start intermittently

91 Bravda 155000 miles TBI 4WD.

Having this "won't start" problem for a while, now seems getting worse.

It won't start once a few weeks when I used to drive almost everyday, but will start easily if let it sit for a few hours. This is situation a few months ago.

Now, I don't drive this Bravada that much, when try to start once a few days, it won't start usually. After I managed to get it started, it will re-start ok then. But after a few days of not driving, it won't start agian.

I heard that the engine of this model gets flooded easily, I tried pressing down the gas pedal for a couple of minutes with switch ON, then start. But still very difficult to get it started, only success a few times.

What do I have to check? How to use the "start fluid" to see if it will start?

Allright!!! Another most cool 1st year of the Bravadas.
Does the engine spin over good or grunt like the battery's down?

It is cranking good and strong, I can crank it for many times, but the engine just won't start.

Can you smell raw gasoline at the tailpipe after trying to start the motor?
If so, we have a spark problem. If not, with the aircleaner off, try pouring 1/4 cup gasoline down the throttle body then try to start. If it runs a few seconds then quits, we have a fuel problem. Keep your battery charged up good, a run down battery kills starters & alternators. Getting a boost for 20 minutes without trying to start the Bravada motor will charge it up nicely.
Let us know.

I wasn't able to start in the previous 2 days, now I can start right away. A puff of light blue smoke always come out the first when motor is started, same happened today. I checked the tailpipe, I think there is strong smell of gasoline when motor is running, after a short while some white thin smoke comes out, and the gasoline odor is gone, in a little longer, the white smoke is gone too, we had rain this morning, humidity is high, that is what cause the white smoke, I guess.

Do you think the spark plugs may need to be replaced? Thanks.

I wasn't able to start in the previous 2 days, now I can start right away. A puff of light blue smoke always come out the first when motor is started, same happened today. I checked the tailpipe, I think there is strong smell of gasoline when motor is running, after a short while some white thin smoke comes out, and the gasoline odor is gone, in a little longer, the white smoke is gone too, we had rain this morning, humidity is high, that is what cause the white smoke, I guess.

Do you think the spark plugs may need to be replaced? Thanks.

the blue smoke at startup is normal on these engines. you might have a leaking fuel injector dripping gas into the engine when off causeing a flooding like symptom. check your oil for gasoline, the oil level will actually go up if gas is leaking down thru the pistons.

When you turn the keyswitch on (not start), can you hear the fuel pump running near the gas tank every time?
Sorry for all the questions, just trying to get more specific.

When you turn the keyswitch on (not start), can you hear the fuel pump running near the gas tank every time?
Sorry for all the questions, just trying to get more specific.
Yes, I can hear the fuel pump running everytime even when the engine won't start up.

I agree with Eric on the blue smoke...valvestem seals don't last forever but it doesn't hurt anything as long as it clears up in a coupla minutes.
Since you hear the fuel pump, the throttle body systems are real reliable and the weather has cooled off lately, I leaning toward an ignition problem. A bad coil gets worse with heat. I heard a little buzzing sound under the hood with the engine running and traced it to the ignition coil.
What are the chances you got a shot of water when you last fueled up?

Eric, how'd yours act when the distributor bearing was going out?

I was able to drive the car for a few times yesterday, meaning on & off a few times without any problems. This morning, engine won't start, I press the gas pedal down while key is in ON for 1 minut or so, engine seemed want to start, it used to be just cranking, engine is not starting, this time, engine want to start but could not, you know what I mean? After a few tries of gas pedal down while in ON, and pressing gas pedal up and down while starting up, I managed to get the engine running. Hope the description is clear enough for you guys to know what is going on, thanks for help.

I will be out of town for a whole week, will check your responses at that time, thanks.

After it starts, is the "Service Engine Soon" light on?

Eric, how'd yours act when the distributor bearing was going out?

cold engine miss fire caused a code 44 from raw fuel being pumped thru. started no problem but felt like it was running on 5 cylinders

After it starts, is the "Service Engine Soon" light on?
No, no SES light at all times.

Ok, no Check Engine light, intermittent start w/ pedal stomping...we need a new start.
Don't pump the gas pedal, try to start the engine but don't turn the motor but about 5 seconds, when it won't start, smell the exhaust pipe for raw gasoline fumes.

Ok, no Check Engine light, intermittent start w/ pedal stomping...we need a new start.
Don't pump the gas pedal, try to start the engine but don't turn the motor but about 5 seconds, when it won't start, smell the exhaust pipe for raw gasoline fumes.
I will try the following:
Don't pump the gas pedal, switch to ON for 5 seconds, then try to start, when it won't start, smell the exhaust pipe for gas fumes.
Correct me if I am wrong, thanks.

Does the engine run good after it finaly starts, or does it misfire, run rough, or seem sluggish? Also how long since you changed the fuel filter? Vehicles that sit for a while tend to get some water condensation in the gas tank that can restrict fuel flow thru the filter.

I will try the following:
Don't pump the gas pedal, switch to ON for 5 seconds, then try to start, when it won't start, smell the exhaust pipe for gas fumes.
Correct me if I am wrong, thanks.

That'll work, I meant to only crank the starter for 5 seconds as in a normal hard start.

Does the engine run good after it finaly starts, or does it misfire, run rough, or seem sluggish? Also how long since you changed the fuel filter? Vehicles that sit for a while tend to get some water condensation in the gas tank that can restrict fuel flow thru the filter.

That's a good thought Eric.

the blue smoke at startup is normal on these engines. you might have a leaking fuel injector dripping gas into the engine when off causeing a flooding like symptom. check your oil for gasoline, the oil level will actually go up if gas is leaking down thru the pistons. Checked the oil, level did not go up. The oil level is actually going down a little bit VERY slowly.

Engine will run good and smooth after started, I don't quite know the symptons of a misfire, but it seems not powerful for a 4.3L engine and big gas eater (comparing to my Camry 2003, maybe the truck is much heavier).

Fuel filter changed about 20 months ago.

This is really a tricky problem, it was cool and damp this morning, and Bravada has been sitting for the past 10 days or so, I expect having difficulties to get it started, guess what? it starts right up, and run fine after a short warm-up. Will keep monitoring and report back, thanks for your help.

You know, reading over this it almost sounds like a fuel pressure bleed down.

Next time you go to start it, prime it by turning the key (without cranking), on, off, on, off, then on and crank. Keep your foot off the pedal.

If it starts the you've got a very small gasoline leak in the lines, whether it be through an injector or a small puncture, though I very much doubt a puncture would go unnoticed.

Josh <><

You know, reading over this it almost sounds like a fuel pressure bleed down.

Next time you go to start it, prime it by turning the key (without cranking), on, off, on, off, then on and crank. Keep your foot off the pedal.

If it starts the you've got a very small gasoline leak in the lines, whether it be through an injector or a small puncture, though I very much doubt a puncture would go unnoticed.

Josh <><
Thanks, will try when it won't start next time, but it has been working fine recently.

I like Josh's thinking, I mentioned it might be a leaking injector in an earlier post. Even though it's running good now you migh try an engine and fuel system cleaner additive like Chevrons Techron. I swear by the stuff.

Can one of the injector heads in a Throttle Body Injector (non-CPI) get the "squirts" ?

Can one of the injector heads in a Throttle Body Injector (non-CPI) get the "squirts" ?

Yep.

Josh <><

Can one of the injector heads in a Throttle Body Injector (non-CPI) get the "squirts" ?

Well, probably not the "squirts". The fuel injector in a TBI is actually just a valve like the spray gun on your garden hose that opens and closes allowing the pressurized fuel to be "injected" or sprayed into the throttle body and be sucked into the manifold in controlable amounts and patterns. The injector doesn't really inject anything, it just opens and closes and like any valve it can stick or fail. If it fails to close all the way when the engine is shut off it will get the "drips", bleeding off the fuel pressure and creating a flooded condition in the engine causing hard starts and white smoke from the exhaust until the overly rich conditions are cleared. CPI units are not immune from this problem either, but if only one sticks the problem is 1/6th as bad on a six cylinder engine and will probably be noticed as a cold start missfire that goes away soon.

In the case of severe leaks or small leaks left to drip for long periods the fuel will get past the piston rings and contaminate the oil, sometimes actualy causing an increase in the volume of the oil in the crank case.

Got something to report today. Has been starting OK in the past few days.

Won't start on the first try today. So I tried Josh's suggestion turning swithch on and off a few times then crank while keep off the gas pedal, no luck.

I then removed air filter, poured some gas down to the valve, try again, still no luck.

With the air filter off, I tried press gas pedal down for a minute or so, then cranked while pressing pedal up & down, after repeated a few times, the engine started turning over, but won't stay on, after a few times, the engine finally stay running, but I think the idle running is rough. So I stopped the engine, put the air filter back, start right up. Ater a while the engine idle runs smooth. Hope this will give you something to check from your past experience, thanks again.

I used MaxVoline fuel injector cleaner last Nov about 5000 miles ago.

Ok... definite flooding condition. When you press the pedal to the floor it seriously leans the mixture to clear the flooded condition.

Pull the plugs and replace them. The number should be CR43TS. You might go up a heat range to CR44TS. Double check though; some models used the regular "R" instead of "CR"

When was the last time you changed cap'n'rotor?

After you turn your motor off, put a piece of paper under the injectors. Inspect it in the morning for fuel stains.

Other things to check would be the fuel pressure regulator and the priming circuit. When you turn the key on it should really dump gas in there, kinda' like a choke on a carb. The key on, off, on, off, on would prime it if the circuits were working, but it sounds like they're OVERworking.

Is it throwing any codes at you?

Josh <><

Ok... definite flooding condition. When you press the pedal to the floor it seriously leans the mixture to clear the flooded condition.

Pull the plugs and replace them. The number should be CR43TS. You might go up a heat range to CR44TS. Double check though; some models used the regular "R" instead of "CR"

When was the last time you changed cap'n'rotor?

After you turn your motor off, put a piece of paper under the injectors. Inspect it in the morning for fuel stains.

Other things to check would be the fuel pressure regulator and the priming circuit. When you turn the key on it should really dump gas in there, kinda' like a choke on a carb. The key on, off, on, off, on would prime it if the circuits were working, but it sounds like they're OVERworking.

Is it throwing any codes at you?

Josh <>< Will try to replace the plugs. Do you suggest to replace cap'n'rotor also? Don't remeber when it was changed.

Just curious, plugs and cap'n'rotor have to do with engine flooding? though fuel injector leaking is the one to blame!?. :frown:

How to fix the "OVERworking" prime thing?

No SES codes at all. Thanks for inputs.

Do you think observing the throttle body injector "heads" for big squirt during a no start event would prove/disprove a big squirt problem instead of a tiny "spitter" for a normal situation?
I'm still holding out for a bad ignition coil.:naughty:

I heard that the engine of this model gets flooded easily, I tried pressing down the gas pedal for a couple of minutes with switch ON, then start. But still very difficult to get it started, only success a few times.

What do I have to check? How to use the "start fluid" to see if it will start?

to clear a flood condition you have to hold the gas pedal down while cranking the engine. here's the description from the chiltons manual:

Clear Flood Mode

If the engine becomes flooded, it can be cleared by opening the accelerator to the full throttle position. When the throttle is opened all the way and engine rpm is less than 600, the computer module will pulse the fuel injector at an air/fuel ratio of 20:1 (early vehicles) or 16.5:1 (later model vehicles) while the engine is turning over (in order to clear the engine of excess fuel). If throttle position is reduced below 80 percent (early vehicles) or 65 percent (later model vehicles), the module will return to the start mode.

so try slamming the pedal to the metal and hold it there while cranking the engine and see if that gets you going.

Will try to replace the plugs. Do you suggest to replace cap'n'rotor also? Don't remeber when it was changed.
YES, replace the cap and rotor! You need to do this every tune up. If you cannot remember the last time they were changed, that indicates to me that could very well be a large part of your problem. When I went to tune up my current Bravada for the first time, it had not been starting, or starting rough, especially when wet. That cap'n'rotor looked almost OEM. I literally had to chisel the rotor off. However, once the cap, rotor, plugs and wires were replaced, everything improved greatly - power, mileage, starting, etc.

Just curious, plugs and cap'n'rotor have to do with engine flooding? though fuel injector leaking is the one to blame!?. :frown:
We're not 100% sure that the fuel injectors are leaking, at least, I didn't see the results of my "paper test." Even if it were, it's acting like weak spark. Those HEI (high energy ignition) systems will burn about anything. The distributor cap and rotor DISTRIBUTES the spark from the coil. If the cap and rotor are bad, it will not distribute properly and with enough EMF to be too awful effective. While you're at Autozone or wherever, they should have specs to test your coil for proper impedence, so take your coil as well. Also check for spalling and other corrosion - such as rust - on the posts and take some fine grit sandpaper to anything you see.

After you get this completed, change out the O2 sensor as it will be gummed up, and you might as well get it changed out while you're at it instead of waiting until it throws a code :2cents: take it for what it's worth. Just a tech here trying to save you hassle.

How to fix the "OVERworking" prime thing?
Let's not jump to conclusions yet. First do the complete tune-up. Do the paper test. If you see any gasoline leaking you will need to rebuild your throttle body unit - much easier than a carburetor and about the same price - and perhaps replace the injectors depending upon if they're leaking as well, and how badly. Could also be your fuel pressure regulator, but let's not go there yet.

Bottom line: Before anything else, complete tune up: Plugs (CR44TS), wires, cap, rotor, and dielectric grease for all external connection. Do NOT put it INSIDE the cap and rotor. Be sure to take along the coil and ignition module as well for testing. Firing order is 1-6-5-4-3-2, rotor turns clockwise. You'll need to know this for reassembly.

Good luck,

Josh <><