guys what should the fuel pressures at the fuel rail read when you switch the car to run and also at off? i'm trying to test if my high pressure fuel pump is o.k. with the fuel system pressurised it goes from 30psi (off) to 37psi (run). i know the 37psi is about right but in the vl workshop manual it says if it "loses pressure appreciably within 60 seconds of switching off, check the high pressure fuel pump". now as soon as you switch the car to off it drops down to 30psi my question is; is this an "appreciable drop in fuel pressure" or is this a normal drop going from run to off? i'm at my wits end trying to find out why my vl wil crank but not fire.. has spark and fuel to the fuel rail. things i have replaced so far is: afm dizzy and crank angle sensor, afm spark plugs coil ecu all fuel relays and fuses. battery as i said im at my wits end now, only thing left to change is injectors and i got some on the way. i hope they are blocked, beacue thats my only hope. any other ideas?

have you checked the timing belt? might be gone

you could be onto somthing there...i did take the cover off and it looked fine but didn't check it had all its teeth, so that will be my next thing to check after swaping injectors over

I would check the belt first, there is a lot more work involved in changing the injectors then taking timing cover off

Quote: Originally Posted by mogila [View Post] I would check the belt first, there is a lot more work involved in changing the injectors then taking timing cover off true, but i just got the feeling that if it was just the timing belt it would be making a better attempt to start then it does, like run a bit rough then snuff out, no? but she wont fire at all. still i might take cover off it and check it out tomorrow, I might as well.

the loss of fuel pressure is nothing to worry about when the car turns off as that will be just pressure releasing through the fuel pump. If you want to stop this use a check valve in the line. Also if the pressure is stable at your 37psi you should have no issues with the fuel side of things. Are your injectors standard? Also if there is spark and fuel the only thing that will stop the car from firing is there is something stoping the injectors from opening and releasing the fuel to the cylinder so my first thing to do is make sure about that.

when u say u checked/changed the afm, did u check the wiring plug? the pins corrode and come out of allignment, I've had issues with this many times as I've had a fair few vl's in the past, best thing is to buy a new boot, comes with new pins which u would need cut the old and splice the new, petroject supply them and deliver to your door. having a dodgy plug can make the car run rough almost to the point where it stalls ---------- Post added 19-01-13 at 21:31 ---------- and when u check the timing belt, crank the engine and see if it turns, might have to get someone to help you here, they crank while you watch the belt

you can buy a can of aerostart to prove if you have a fuel delivery issue. if the spark plugs are wet the engine won't fire up. it may try and chuggle then stall out every now and then. fuel pressure from 26psi up will fire the engine. normally at idle with a stock camshaft, the fuel pressure will be 36psi and drop to 30 when pumps are off. it will hold 30 -ish for a minute or two if the one-way ball valve is doing its job. From experience, it's not pressure in the line that matters. its actually fuel. if the tank is low or one the pumps (usually intank) is faulty, the pumps can still pressurize the fuel line but it won't hold for more than a few seconds after power to pumps is removed.

Quote: Originally Posted by grunter01 [View Post] the loss of fuel pressure is nothing to worry about when the car turns off as that will be just pressure releasing through the fuel pump. If you want to stop this use a check valve in the line. Also if the pressure is stable at your 37psi you should have no issues with the fuel side of things. Are your injectors standard? Also if there is spark and fuel the only thing that will stop the car from firing is there is something stoping the injectors from opening and releasing the fuel to the cylinder so my first thing to do is make sure about that. yeh i think its safe to say with the fuel pressure to the rail good, and the plugs dry when i take em out after cranking, it must be the injectors aren't pulsing for some reason. yep they are stock injectors. the car was running fine and all i did was park at up in the shed and let its sit for a month, then go to start and it cranks but thats it. will also check the afm plug, but i think they can still start with a no signal from the afm but go into limp mode?

ye car will run without afm hooked up, only on idle, when u gass it cuts out. car has been sitting for a month? full has gone off maybe? I've never had issues with my car sitting for over a month but it's worth investigating.

has go to do with the injectors not pulsing so get it checked from an auto elec

There is fusesable links that run off the positive battery terminal one set if for the injectors had the same problem as this got another set put them in and car cranked up even try wiggle them and see if it starts

Quote: Originally Posted by rb25vlt8 [View Post] There is fusesable links that run off the positive battery terminal one set if for the injectors had the same problem as this got another set put them in and car cranked up even try wiggle them and see if it starts already tried that, swapped with another vl

Unplug all the injectors with your reds on see if there is power at either side of injector plug . I really don't think all your injectors would stop working after one month of sitting around . It got to be more simple than that . Let me know if ther is solid power on one side of injector plug . Unplug them all tho just to be sure . There must be power constantly on one side with the reds on the computer supply's the ground pulse . If ther is power use a led test light to the positive batt terminal and see if u get a pulse if so computer is grounding the injectors .

Quote: Originally Posted by ROB2019 [View Post] Unplug all the injectors with your reds on see if there is power at either side of injector plug . I really don't think all your injectors would stop working after one month of sitting around . It got to be more simple than that . Let me know if ther is solid power on one side of injector plug . Unplug them all tho just to be sure . There must be power constantly on one side with the reds on the computer supply's the ground pulse . If ther is power use a led test light to the positive batt terminal and see if u get a pulse if so computer is grounding the injectors . ok ill do this tomorrow but what do you mean by "with your reds on"

Quote: Originally Posted by wlk21 [View Post] ok ill do this tomorrow but what do you mean by "with your reds on" With the ignition switched on so the battery light and so on is on the dash board . Then check the power at the injector plug with ignition on there should be 12 v at the injector plug constant Some original photos have not been recovered yet.

The distributor connector can cause a loss of injector pulse also. out of the 4 wires in it, power-orange, gnd-black, inj pulse-white, spark pulse-orange. if the connector looks crusty and corroded it will cause this if all other fuseables and relays are ok. check the o/s engine mount has 3 black gnd wires all on the same bolt also.

couldn't find my multimeter but got out the test light and cylinder one injector lights up on one pin, cylinder 2 lights up on both pins?? is this not normal? ..anyway i will keep looking for my multimeter and take plenum off to get to all the injectors, and also have a look at dizzy plug ---------- Post added 21-01-13 at 15:59 ---------- well it seems i was too quick to rule out spark...i thought i might check it one more time before pulling everything down just to be sure. i pull out first lead and connect to a spare plug and crank it, and sparks maybe twice and then nothing....same thing next cylinder! ...so ive changed dizzy 3 times, coil twice, pt twice, ecu twice...looks like i'm up for a new set of leads to rule that out now agghhh!!! don't you just love vls? i will give up soon

If there is power at one or two it should be ok . That's not goin to rule out a high resistance sum where..But not likely the problem . I'm still thinking sum thing with injection since u say the plugs are dry . but if its not sparking also its gotta be the dizzy or dizzy plug or ecu but u say u have changed all of that ! Try putting the coil lead near ground and see if that sparks jus try not to get sapped Some original photos have not been recovered yet.

Quote: Originally Posted by ROB2019 [View Post] If there is power at one or two it should be ok . That's not goin to rule out a high resistance sum where..But not likely the problem . I'm still thinking sum thing with injection since u say the plugs are dry . but if its not sparking also its gotta be the dizzy or dizzy plug or ecu but u say u have changed all of that ! Try putting the coil lead near ground and see if that sparks jus try not to get sapped haha yeh one step ahead of ya, a couple of weeks ago i pulled the lead off the coil just enough to see if the spark would jump across and yep sure did, i got a nice belt out of doing that too lol so yeh i've changed all things to do with spark, coil, ecu, pt, and lead going from coil to dizzy...ive got a new set of leads on the way but i doubt thats going to solve things tbh. so i don't know what else there is to do really...got a new set of injectors to plug in but whats the point if i can see it aint sparkin..just tried the spark test again and it sparks once when you first turn the key then nothing. i'll be extrememly pissed if this is some sort of a wiring problem. ---------- Post added 23-01-13 at 14:47 ---------- ohh and i've done the diagnostics mode with the ecu and it throws out an ignition circut fault which doesn't really narrow things down enough. Some original photos have not been recovered yet.