Hey guys, after sitting in a parking lot at work for about 4 weeks, my 03 cav wont start. Before this, the car seemed to run perfect. When i crank it, it sounds like it almost starts but then just dies and continues cranking off the starter. Here are my observations so far:
*Checked spark on cylinders 3 &4, appeared good. Didn't check the other 2
*Fuel pump turns on when i turn the key on and stops at about 58 PSI. The pump sounds normal.
*Fuel pressure seems to drop quickly. I don't know how long fuel pressure should hold, but i imagine there is some sort of safety designed into the FPR to bleed the system down. It seems i lose about 10 psi in about 5 seconds.
*When i turn the key to crank, the fuel pump does not turn back on and fuel pressure drops.
*The spark plugs were not light in color, but seemed maybe a tad dark.
So my questions are:
*What is considered a normal bleed time for fuel pressure?
*Is the fuel pump supposed to turn on during crank? If so, what would cause it to turn off?
*Are there any tests I can do to narrow down the cause some more?
Additional information:
Car has a weapon R secret weapon intake on it. It's been on since about 40k miles. The car currently has 161k miles. There are no other engine or fuel mods on the car. The fuel pump was replaced at 48k with an OEM GM pump. Spark plugs, timing chain & tensioner were replaced at 124k with OEM GM parts. Fuel filter was replaced somewhere between 100k and 124k ( i don't remember).
I'm thinking I should replace the fuel filter just to be safe, but I can't image that would cause the fuel pump not to turn on.
Sorry for the long post, but I tried to think of what everybody would be asking and 'front-load' information rather than waiting for people to ask.
Thanks!
Ok, so i just went out with the gauge again, and it seemed to hold pressure fine this time. I must have just had a bad connection to the gauge. Still would not start though, even when sprayed with starting fluid.
Next step is to check if the injectors are working. After that I will run a compression test.
how did you hook up a pressure gauge tot he fuel? any pictures?
I just wonder how I could measure mine, then I would know how your pressure drop compares to mine.
There is a cap on the fuel line coming from the tank. you just take off that cap and put the correct adapter from your fuel gauge kit. The valve is on the right side of the engine if you're looking at it from the front.
So, I checked compression, and got 65-110-120-140. They all seem low.
well, i took off the valve cover and found that the intake cam diamond isn't pointing to the blue link on the chain, and same goes for the exhaust cam square and the red link on the chain.... so question is, how could this have happened? see below:
the square exhaust marker is barely visible in the second pic at about 7 o'clock.
Well, replace your chain and tensioner, and see what happens next. It's not uncommon for these chains to jump a tooth.
Are u sure that you were not 180 out of phase on the cams? If yes rotate the engine another rotation to see if this is the case or cyl 1 should be at tdc
just so you know, after timing is properly set, it will take something like 180 complete revolutions of the chain for them to line up again. but timing is easy enough to set. reset it and call it a day.
I'm not understanding what you're saying. This chain has been on the car for 40k miles and running fine. I haven't messed with the timing since installing the chain. Are you saying i should crank it around again and see if the markers line up?
Thanks for the help.
So i went out and rotated the crank another 180, and the marks were still way off. So i guess it's time for a new chain and pensioner and to pray to the car gods that the valves are still good..
What I am saying, is that the mark you speak of will only line up when you set timing in the beginning. They are there just to set timing during a build, or while replacing the chain or a tensioner or something. They are not designed to always line up after the engine is run. So just because those marks do not line up, doesnt mean that your car is not timed properly. I would say that you need to worry about why compression of 65 on cylinder one is way way way way way way way too low. The others are low as well, but some might say could be acceptable on a motor with that many miles. A master tech once told me that GM says anything 30% lower then what is considered stock compression is acceptable on a motor with 100k or more miles.
EvoFire wrote:What I am saying, is that the mark you speak of will only line up when you set timing in the beginning. They are there just to set timing during a build, or while replacing the chain or a tensioner or something. They are not designed to always line up after the engine is run. So just because those marks do not line up, doesnt mean that your car is not timed properly. I would say that you need to worry about why compression of 65 on cylinder one is way way way way way way way too low. The others are low as well, but some might say could be acceptable on a motor with that many miles. A master tech once told me that GM says anything 30% lower then what is considered stock compression is acceptable on a motor with 100k or more miles.
I'm a Gm tech. Let me clear that up. Gm states that compression must be over 100 psi and at least 70% of the best cylinder.
Dave De Stefano wrote:EvoFire wrote:What I am saying, is that the mark you speak of will only line up when you set timing in the beginning. They are there just to set timing during a build, or while replacing the chain or a tensioner or something. They are not designed to always line up after the engine is run. So just because those marks do not line up, doesnt mean that your car is not timed properly. I would say that you need to worry about why compression of 65 on cylinder one is way way way way way way way too low. The others are low as well, but some might say could be acceptable on a motor with that many miles. A master tech once told me that GM says anything 30% lower then what is considered stock compression is acceptable on a motor with 100k or more miles.
I'm a Gm tech. Let me clear that up. Gm states that compression must be over 100 psi and at least 70% of the best cylinder.
that could have been what he said too! lol either way it got the point across...
EvoFire wrote:Dave De Stefano wrote:EvoFire wrote:What I am saying, is that the mark you speak of will only line up when you set timing in the beginning. They are there just to set timing during a build, or while replacing the chain or a tensioner or something. They are not designed to always line up after the engine is run. So just because those marks do not line up, doesnt mean that your car is not timed properly. I would say that you need to worry about why compression of 65 on cylinder one is way way way way way way way too low. The others are low as well, but some might say could be acceptable on a motor with that many miles. A master tech once told me that GM says anything 30% lower then what is considered stock compression is acceptable on a motor with 100k or more miles.
I'm a Gm tech. Let me clear that up. Gm states that compression must be over 100 psi and at least 70% of the best cylinder.
that could have been what he said too! lol either way it got the point across...
Yea, Gm's tolerances for this are ridiculous. Most manufacturers would have like, 155-168 psi. But if one cylinder is 100, and another is 135 its borderline acceptable.
I figured the timing being off could cause the low compression, as the vehicle seem to drive fine before this. If it's not the timing, what could it be??
ok, well it turns out the the oil was washed away from the cylinder walls due to sitting for a while and trying to start on a cold day (more fuel due to temperature). so a cap full of oil in each cylinder through the spark plug hole fixed it. it runs great. I just took it from detroit to west virginia and got 33 mpg with 3 guys in the car and the A/C blasting
