2001 Bravada Will not stay running and no power at all

[Calsar]

Hello,
I have a 2001 Bravada (123k miles) that Im hoping for some advice on. The vehicle had always ran fine then it started to occasionally get a hiccup while driving down the highway. Best way I can explain it is just a split second there was no power at all and then it recovered just as fast so it just felt like a brief shudder. This went on for about a couple weeks. Then the wife was driving home from work and it just started losing power. It died on her at a stoplight and some folks helped her push it into a nearby parking lot. So when I arrived, tried to start it and it would fire up and sputter terribly. RPM would bounce between 800 and 400 erratically. Try to give it gas and it would make it just over 1100 before it would cough and die. Tried to put it in gear and feather the gas to get it to move but it doesnt even have enough power to slug itself along. Had to wench it onto a trailer, it couldnt get there under its own power. Installed new cap set, plugs and wires. No change whatsoever. The only code that is showing is P0300. Generic random cylinder misfire detected. With that being the only code showing, Im honestly a bit at a loss as to where I should even start looking. Any help at all as to where to start looking would be greatly appreciated.

[Chris Stewart]

Welcome to the site.
Good work on the tune up, it helps most of the time with me.
It looks like a rash of this is occuring lately. Lack of sufficient fuel pressure has been the problem with many and likely is your issue too.
A fuel pressure check is in order, the pressure spec. is 61-65psi.
There are test kits available at most auto parts stores for around $40 and Harbor Freight sometimes has them at a lower price.
Here's where to check yours,



Be aware that if a fuel pump replacement is in order, use only the Delco brand pumps as other pumps appear to be failing, often as soon as they're installed.
Let us know what you find.

[Calsar]

Thank you for the information. Just want to clarify a few things , so I apologize if the questions seem simple. Low fuel pressure could cause the P0300 misfire code? I guess I dont really understand what its detecting so just making sure that if the fuel pressure is the issue that the code isnt another one in wait. And as for checking the fuel pressure, Im assuming that that test port should be at the correct pressure when the key is on and would not need to be running? Thanks again for your help, will pick up a pressure tester tomorrow and see what it says.

[GunsOfNavarone]

Sounds like it could also be the ignition switch. The problems like dying at hwy speeds and then recovering, and dying at a stop sign are all symptoms of an intermittent failure of the ignition switch. This is a very common problem in the Bravada, I hae replaced the switch twice.

[Chris Stewart]

The P0300 is like you say, it's a random missfire...not 1 particular cylinder is missing. It's amazing that at speed the computer can detect which cylinder is missfiring but I guess it can with all the input info.
Yes, the pressure must be checked with the keyswitch on. The pump will run for a few seconds then stop but there's a check valve that should hold pressure for a few minutes after the pump shuts off.
I agree that it seems like it could just dribble in any bit of fuel to idle but evidently the fuel must meet spec to squirt...all help gratefully accepted.

If you have a pal with a '98.5-'02 Dodge w/Cummins diesel, the test kit can check their lift pump fuel pressure before lack of sufficient pressure destroys the $1030 injector pump.

The keyswitch has been an issue like GunsOfNavarone says too.
Maybe wiggling the keyswitch while the fuel pump is running to see if that affects run time can help spot that problem.

[Calsar]

Hello,
Sorry for the late reply. Took awhile before I had any time off to work on the Bravada. I picked up a fuel pressure tester and checked it out. The pressure is reading 58 lbs. While I realize that is 3 lbs under the listed spec that you gave, would that be a drastic enough loss of fuel pressure to keep the vehicle from even being able to hold an idle or pull itself across the driveway? Thanks in advance for your time and assistance.

btw- I did try working with the key while starting with no noticeable difference.

[Leeann94astro]

Yes, 3 lbs can make a world of difference.

[duke350]

I have seen them run with 40 psi, but would not start without being primed and did not have full power, but it saved the tow bill for the few blocks it was away from a place to work on it. Not reccommended, but it is possible. When you check the pressure you need the number the gauge is at when the pump is running. As stated, the pump will run for a couple of seconds to prime when the key is first turned on. There is a check valve in the pump which holds pressure, but it will drop a few lbs from full after the pump shuts down. It should then hold pressure for a while. Also, when was the last time the fuel filter was replaced? This can affect fuel pressure. If the fuel filter was not checked/changed regularly it can lead to fuel pump failure. If it were me, I would change the filter if it has been a while and check the pressure again. It may even be all that is wrong, as pressure and volume are two totally different thing. Again, try the filter first and see if that helps. It only takes 15 mins or so and is about $5. And it sure couldn't hurt.

[Calsar]

duke350,
I will try a filter and see if that makes any change. As for the fuel pressure reading of 58 lbs, that was taken after the pump had already kicked off. I did not actually have someone turn the key while I was watching the gauge. I turned the key on then got out and went to take a look. It was 58 lbs at that point and maintained that 58 lbs steady for the length of time that the gauge was left on the car. Will try tomorrow and see what it reads at the time the pump is actually running. If it drops a few pounds when the pump turns off, then I may very well be at the 61 lbs when the pump is running. Will check it out after work and let everyone know what I find out. Thanks again for everyones time and assistance.

[Calsar]

Ok tried the fuel filter and there was no change in the way the vehicle ran... or didnt run I guess you could say. As for the pressure, I checked the gauge while someone turned the key on and it went to 66 lbs and dropped to 58 lbs as soon as the pump turned off. So based on what has been said here, Im taking it that the pump is operating as it should be? Any suggestions as to what would be a good next step to check? Thanks in advance for your time and advice.

[GunsOfNavarone]

I have had the exact problem you experienced twice. Both times, ignition switch. Cost about 120 at Napa and fairly easy to replace. You will need a special sized torx. You do not have to remove the steering wheel- I actually repalced one in the parking lot of a Kohl's department store (and I am not a mechanic).

[Calsar]

Guns,
At this point, I will give it a try. But I have a question... in your earlier post, you mentioned dying at stop signs and dying and recovering at highway speeds. I can understand the ignition switch causing a total loss which would cause the vehicle to die and such.. but would it be an all or nothing deal with ignition switch? Because I can get it to start... it just cant hold an idle and doesnt even have enough power to pull when its put into gear. It is still running though.

[duke350]

Before you buy a new switch, test it with a test light or meter. Your pressure sounds fine. You need to make sure you have fuel and ignition in the cylinders. Check a couple of plugs for good hot blue spark. Try to prime it with carb cleaner to see if it will fire. If its not running something is missing. Either fuel, fire or time. Fuel and fire are the fast easy checks.

[Calsar]

duke350,
Thanks for the suggestions. I guess I should post a littl more on what I checked when I did the tune up when problem first arose. I did bring number 1 cyclinder to top and checked the cap. Rotor was pointing in the correct position. At the time I changed plugs, I did check for good fire as I had though it could have been bad spark. I have not tried to spray it with anything, will give that a try. Perhaps a silly question considering I have no codes thrown for it, but what would be the effect on the engine performance if the cat. cov. was plugged badly? Had it running today although it was coughing and sputtering and noticed the exhaust had a poor smell and it seemed as though there was very little pressure coming from the tailpipe. As I said, maybe its a silly question, but just curious.

[duke350]

A (usually) quick test for that would be to pull the O2 sensor(s) before the cat and see if it runs better. You can also check (if you can get/keep it running) vacuum at idle and about 2000 RPM. The reason to try to spray some carb cleaner (never use starting fluid on these) is the injector may be clogged or just not firing. As for the switch, I am not sure on the newer ones, but 97s had all kinds of problems.