starting problem fuel related

[derhells]

Here is my issue I have a 93 bravada that will run like new and does all i ask of it but if it sits for more than 5 hours it take forever to start. this is a new problem for me and it is the only real problem I have had with this truck. I replaced the fuel filter and it was clogged, thought I had the problem licked but then 5 hours later it took me over 20 turns of the key to get the thing running again. Spark is fine and all the plugs wires cap and rotor have been changed in the last 3 months. problem with the start has only been happening for the last 2 weeks getting worse every day. Any help????

[Chris Stewart]

Has the Check Engine light lit up yet?

[derhells]

Originally Posted by Chris Stewart

Has the Check Engine light lit up yet?

No I have not had the check engine light on. I have looked at a lot of your responses and you know what you are talking about so any help would be great. Here are some more of the things I have had happen that are related to this problem. First I thought the transmission was going as it was not shifting correctly (automatic) was not shifting down when I stopmed on it. Then the starting problem happend. Would take three to four times to get it started. 1 st try would geee gee geee. then gee gee gee uggg, then gee ugg ugg then gee vruuum it would start this was only after the car sat for more than 5-6 hrs. This slowly got worse over about a two week period. till i had nothing but gee gee gee. I can still get it started but takes like 20 tries. I am getting spark. Changed the fuel filter and it started right up ran it and it shifted fine (think it was lack of fuel to the engine causing the engine to use all the fuel and then not have enogh left to let the engine till the transmission to stop) the filter was clogged!! after it sat for about 5 hours it would not start again for about 20 tries. My out look so far is pressure relief valve, poor pressure from feul pump, or clogged injectors. please help this is my baby I have had it since 150,000 and now has 184,000 I want to hit 200,000. I have not brought it to a mechanic in the three years I have been driving it and do not plan on it. I have done plenty of work myself and when I get this solved I am going to help others the way you do. Thanks Derek

[Chris Stewart]

If you get a "futt-hooey" after the "uggg" then your distributor cap has condensation in it.

Assuming you have the CPI fuel injection, does the exhaust pipe have a strong gasoline odor? If not then your fuel pressure problem has returned and the fuel pressure needs checking with a pressure guage...50 to 55 psi is normal.
If the odor is strong, you're likely to have a major fuel leak inside the intake plenum, either the injection unit or fuel supply lines...I think all CPI motors eventually suffer this but the repair is not too complicated.

[derhells]

Originally Posted by Chris Stewart

If you get a "futt-hooey" after the "uggg" then your distributor cap has condensation in it.

Assuming you have the CPI fuel injection, does the exhaust pipe have a strong gasoline odor? If not then your fuel pressure problem has returned and the fuel pressure needs checking with a pressure guage...50 to 55 psi is normal.
If the odor is strong, you're likely to have a major fuel leak inside the intake plenum, either the injection unit or fuel supply lines...I think all CPI motors eventually suffer this but the repair is not too complicated.

I do not have the smell of gas in exhaust. I will change the cap, but everytime i have tested i am getting spark. I will have to get a pressure tester and test the pressure of the fuel pump. This will suck if it is the fuel pump, as I just changed the tank this summer and that was not all that fun!! Thanks any more insight?

[Chris Stewart]

Regarding spark, the spark must occur at each cylinder & exactly the correct moment and it must be enough voltage to fire the sparkplug under the conditions of high air pressure (compression pressure...140psi) and in the presence of wet gasoline.
Condensation or water droplets inside the distributor cap will conduct electricity to the wrong cylinder giving you the "uggg'.
A gradual weakening of the spark voltage due to the ignition coil going bad will keep the warm motor from restarting until the coil (and motor) cools off.

[derhells]

Originally Posted by Chris Stewart

Regarding spark, the spark must occur at each cylinder & exactly the correct moment and it must be enough voltage to fire the sparkplug under the conditions of high air pressure (compression pressure...140psi) and in the presence of wet gasoline.
Condensation or water droplets inside the distributor cap will conduct electricity to the wrong cylinder giving you the "uggg'.
A gradual weakening of the spark voltage due to the ignition coil going bad will keep the warm motor from restarting until the coil (and motor) cools off.

My start problem only happens when it has been sitting for a long time about 5 hours is enough for it to need 5-6 tuns of the key to get it started. overnight and I am looking at 15-20-nostart before patience runs out. I will be changing the cap as I see your point on that. I will be doing that in about an hour and will tell you if it does anything. I have been reading my book and wonder if it is the pressure release valve is stuck open and this allows all of the fuel to drain back into the tank after a certain amount of time and thus it takes forever for the pump to return the fuel to the engine for firing? Let me know what you think of this theory. And where the hell is the release? Bet I will have to drop the tank to get to it. I will change the cap and rotor and see what the outcome is first before I start chasing other things. thanks derek

[Chris Stewart]

There is continous flow from the fuel pump in the fuel tank to the injector then back to the fuel tank whenever the pump is running.
You can check the distributor cap for condensation...no moisture, white junk or cracks, don't replace.
I don't know of any pressure release valves in the system. There's a pressure regulating device on the injection unit inside the intake manifold on a CPI fueled motor.
Does your engine have a big plastic cover on top of the motor that says "Vortec" ?

[derhells]

Originally Posted by Chris Stewart

There is continous flow from the fuel pump in the fuel tank to the injector then back to the fuel tank whenever the pump is running.
You can check the distributor cap for condensation...no moisture, white junk or cracks, don't replace.
I don't know of any pressure release valves in the system. There's a pressure regulating device on the injection unit inside the intake manifold on a CPI fueled motor.
Does your engine have a big plastic cover on top of the motor that says "Vortec" ?

Yes the motor says vortec on it. I changed the cap and rotor last night and it started right up. I however did not hold my breath all night and low and behold it did not start this morning. I pulled the fuel filter again and it was fine, thought the new one I put in may have gotten clogged, but no such luck!!! While I had it off I tested the fuel pump with a pressure gauge and it was way high off the board pegged at 100 psi. not sure if that is because I tested it at the filter? I am going to test it at the tester valve and see what I come up with. The pressure did however hold steady for the 3-4 minutes I left the gauge on. I read that if I test the pressure at the tester valve and I have the same outcome that the return line may be clogged or the cmfi is bad. What the hell is the cmfi? I will not be getting to that for a few hours though as my 2 month old is up from her 1 hour nap, I need to wait for her to go down again this afternoon. Thanks Derek

[Chris Stewart]

The CMFI reference is probably refering to the fuel injection which is a CPI on our older Bravadas ..Central Point Injection.
Pegged a 100psi pressure guage? There's a fuel line pinched somewhere unless a big piece of junk lodged in the regulator which is part of the CPI inside the intake manifold. I agree with your test at the Schrader valve.

[derhells]

Originally Posted by Chris Stewart

The CMFI reference is probably refering to the fuel injection which is a CPI on our older Bravadas ..Central Point Injection.
Pegged a 100psi pressure guage? There's a fuel line pinched somewhere unless a big piece of junk lodged in the regulator which is part of the CPI inside the intake manifold. I agree with your test at the Schrader valve.

I am having a hell of a time finding a fuel pressure gauge to test at schrader valve. Also can you just change the regulator or clean it? I heard that for a new cpi it is like $800 that is not worth it to me on a truck with 184,000. If I am not smelling gas the lines are not leaking, so what else should I be looking for? I know I need to test the pressure again at the schrader valve but in the mean time I would like to check other things if I can any suggestions?

[Chris Stewart]

Can you hear the fuel pump start when you turn the keyswitch on?
You could run a diagnostic to see if the computer has any trouble codes stored...
Here's how to check a '91-'94 Bravada for trouble codes:
Jumper the 2 top right hand holes on the assembly line diagnostic link(ALDL)under the steering column-lower dash area then turn on the ignition switch and count the check engine light flashes. You'll get a single then double flash...1-2 or code 12 three times which means the computer is saying "Ok Pal, I'm gonna tell ya any trouble codes stored". Any codes stored will flash 3 times.After all the codes stored are shown you'll get another set of code 12's which let's you know "that's all folks" unless you want to see again which it'll then just keep reporting the stored codes. When you get through, just cut the ignition switch off and pull your jumper wire. To reset the check engine light, disconnect either battery cable for 15 to 20 seconds.Let us know what codes are stored and we'll discuss what's the problem.

[derhells]

Originally Posted by Chris Stewart

Can you hear the fuel pump start when you turn the keyswitch on?
You could run a diagnostic to see if the computer has any trouble codes stored...
Here's how to check a '91-'94 Bravada for trouble codes:
Jumper the 2 top right hand holes on the assembly line diagnostic link(ALDL)under the steering column-lower dash area then turn on the ignition switch and count the check engine light flashes. You'll get a single then double flash...1-2 or code 12 three times which means the computer is saying "Ok Pal, I'm gonna tell ya any trouble codes stored". Any codes stored will flash 3 times.After all the codes stored are shown you'll get another set of code 12's which let's you know "that's all folks" unless you want to see again which it'll then just keep reporting the stored codes. When you get through, just cut the ignition switch off and pull your jumper wire. To reset the check engine light, disconnect either battery cable for 15 to 20 seconds.Let us know what codes are stored and we'll discuss what's the problem.

I can hear the pump runnig both when I turn the key and after trying to start. I ran the codes and got nothing but 12's across the board. This is starting to get difficult but I would really like to solve this issue and keep on trucking. Any other suggestions. I have a fuel pressure tester coming on sunday so that gives me time to chase down anything else you may be able to come up with. Thanks Derek

[derhells]

Originally Posted by derhells

I can hear the pump runnig both when I turn the key and after trying to start. I ran the codes and got nothing but 12's across the board. This is starting to get difficult but I would really like to solve this issue and keep on trucking. Any other suggestions. I have a fuel pressure tester coming on sunday so that gives me time to chase down anything else you may be able to come up with. Thanks Derek

This is such a intermitent problem, (no start) today I get home from work, have not started it for about 24 hours first turn of the key and the thing fires right up like nothing is wrong. I have had it running in the driveway for about two hours, thing is running like always. I have shut it down and let it sit for about ten minutes and it still fires right up. I am going to let it run for another couple hours and then pull it back into the garage and let it sit all night and see what tommorow will bring. Could it be that I just have a bunch of shit in the fuel line and that is why it will only not start when the stuff is in the way? I had just put a bottle of injector cleaner in the tank the first day it really gave me the no start about 30 turns of the key and some of that with a jumper box attached, wonder if the cleaner is starting to take effect. I know that sounds like wishful thinking but wierder things have happened. I will let you know what the fuel pressure reading is when I take it in the morning if I still have a no start. Thanks again Derek

[jnpeak]

Couple things I can tell you to check that might help find out what's going on:

First, if you try to start it and it doesn't want to, take your fist or a rubber mallet and hit the bottom of the tank in the area where the pump is while someone else is turning the key to try to start it. If this gets it to start it's most likely the fuel pump. If your using the mallett don't hit it too hard. This may get it to start if it's the pump but it's not a trick you can use for too long, it's only a matter of time before the pump won't work at all.

For a check on the injection unit/hoses, change your oil, if it's thin and smells like gas it's most likely that. Also pull a plug from both sides and look at them. One other thing you can do is pull the EGR valve and with a light look inside the intake. If you see gas spraying then it's the injection unit or the hoses. You should be able to do this with the key on without it running because your head will be right near the fan.

Have you tried giving it gas when your trying to start it? When my injection unit went it first started out starting hard, then progressively started running worse, mileage fell off, gas in the oil, but it wasn't throwing any codes. Your symptom is much like mine in the early stages and many, if not all the people on here with that year Vortec has had to change the injection unit or some part thereof and/or the hoses.