loubotzz77
New member
whats up guys question about fuel pressure when i turn my ty on i get 43 psi and then it drops down to 0 its not holding fuel pressure amy ideas??
fuel pressure
- Thread starter loubotzz77
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SY756
New member
Re: fuel pressure
Does it only drop to 0 when you shut off the key? If it does that I had the same problem on my DD blazer. The "o-ring" on the pulsator had blown out causing the pressure to be there but not the volume and when I turned the key off all the pressure would leak back through the o-ring into the tank. Truck would idle but not run under load.
The other thing I can think of is the diaphram in the FPR has a tear or hole in it. Anyway about it there is a leak in the system somewhere.
loubotzz77 said:
Does it only drop to 0 when you shut off the key? If it does that I had the same problem on my DD blazer. The "o-ring" on the pulsator had blown out causing the pressure to be there but not the volume and when I turned the key off all the pressure would leak back through the o-ring into the tank. Truck would idle but not run under load.
The other thing I can think of is the diaphram in the FPR has a tear or hole in it. Anyway about it there is a leak in the system somewhere.
dirtdemon
"mr. ghettowrench"
Re: fuel pressure
X2
had kinda same problms with my truck, thats how i blew my first engine :tdown:
figured out that a bad fuelpump was the cause ...
now i have similar probs, but in a different way - fuelpress is quit fine, but at WOT fuelpress is odd ...
.. hope after i swap the FPR once again it will be fixed (thx turbodig, btw.)
let us know what ya prob was, when you have sucess
opcorn2:
pat.
EDIT : AND - like SBNova said already, leaking injectors is an option, too IMO !!
SY756 said:
X2
had kinda same problms with my truck, thats how i blew my first engine :tdown:
figured out that a bad fuelpump was the cause ...
now i have similar probs, but in a different way - fuelpress is quit fine, but at WOT fuelpress is odd ...
.. hope after i swap the FPR once again it will be fixed (thx turbodig, btw.)
let us know what ya prob was, when you have sucess
opcorn2: pat.
EDIT : AND - like SBNova said already, leaking injectors is an option, too IMO !!
loubotzz77
New member
Re: fuel pressure
the fuel pressure jumps up to 43 and then with key still on it drops to 0 psi any ideas??
the fuel pressure jumps up to 43 and then with key still on it drops to 0 psi any ideas??
midnightbluS10
Banned
Re: fuel pressure
replace the fuel pump and don't use the pulsator.
replace the fuel pump and don't use the pulsator.
dirtdemon
"mr. ghettowrench"
Re: fuel pressure
the pulsator has no potential to cause problems IMO, when it's fine - nothing happens, when it's bad - will work like w/o pulsator (diaphragm blown) ...
btw.: my FP came with an description that said defenitly REuse the pulsator (255 FP from RPM)
HTH, pat.
midnightbluS10 said:
the pulsator has no potential to cause problems IMO, when it's fine - nothing happens, when it's bad - will work like w/o pulsator (diaphragm blown) ...
btw.: my FP came with an description that said defenitly REuse the pulsator (255 FP from RPM)
HTH, pat.
Re: fuel pressure
When my Ty wouldn't hold FP it turned out to be the pulsator. The rubber compound in the pulsator was deterioated and cracked when I removed it. As a result alot of the fuel that the pump was attempting to send to the engine wouldn't even make it out of the gas tank because it was leaking out of the pulsator. There may be a TSB on the pulsator problem. I remember my mechanic giving me some information which lead me to the pulsator when he tried to diagnose my engine/fuel problems. It said something about the rubber compound in the pulsator being deteriorated by different grades of gas.
When my Ty wouldn't hold FP it turned out to be the pulsator. The rubber compound in the pulsator was deterioated and cracked when I removed it. As a result alot of the fuel that the pump was attempting to send to the engine wouldn't even make it out of the gas tank because it was leaking out of the pulsator. There may be a TSB on the pulsator problem. I remember my mechanic giving me some information which lead me to the pulsator when he tried to diagnose my engine/fuel problems. It said something about the rubber compound in the pulsator being deteriorated by different grades of gas.
Re: fuel pressure
yes,pulsators failed constantly. They made me alot of $ like 10 years agn the cpi 4.3 engines the injectors wouldnt even work with less psi than like 55 so as soon as the pulsators would begin leaking the trucks wouldnt even start.the replacement black pulsator seemed to hold up better than the red ones.alot of times I would jump it with a rubber hose to save the customer $50.00 never had a come back or complaint.
I recently pulled the tank on my sy to see what pump the previous owner had put in it. it is a 255 walbro with no pulsator,give me a reason to put one in that would benefit the system,I thought they were just there to make the pump less noisy???
yes,pulsators failed constantly. They made me alot of $ like 10 years ag
n the cpi 4.3 engines the injectors wouldnt even work with less psi than like 55 so as soon as the pulsators would begin leaking the trucks wouldnt even start.the replacement black pulsator seemed to hold up better than the red ones.alot of times I would jump it with a rubber hose to save the customer $50.00 never had a come back or complaint. I recently pulled the tank on my sy to see what pump the previous owner had put in it. it is a 255 walbro with no pulsator,give me a reason to put one in that would benefit the system,I thought they were just there to make the pump less noisy???
loubotzz77
New member
Re: fuel pressure
i also found another problem im getting a very low spark i looked at the pickup coil in the distributor and it looks like shit so i yanked out my distributor and im putting in a new 1
i also found another problem im getting a very low spark i looked at the pickup coil in the distributor and it looks like shit so i yanked out my distributor and im putting in a new 1
Rexxenexx
Active member
Re: fuel pressure
loubotzz77 I've just ran into this problem 10min. ago. When you turn the key it goes up then it goes to zero. I put a gauge on the rail and turned the key on + jumped the pump cable to hold it and I see 30psi. This is with a stock regulator and a 255hp walbro intank (racetonix kit I installed about 2-3 years ago). The car won't start. It almost did like two times out of a bunch of tries. Update us on your progress.
loubotzz77 I've just ran into this problem 10min. ago. When you turn the key it goes up then it goes to zero. I put a gauge on the rail and turned the key on + jumped the pump cable to hold it and I see 30psi. This is with a stock regulator and a 255hp walbro intank (racetonix kit I installed about 2-3 years ago). The car won't start. It almost did like two times out of a bunch of tries. Update us on your progress.
Rexxenexx
Active member
Re: fuel pressure
I got it started today but it seems to still have the problem. I put 5gal of gas with 3oz of stabil and also put the gauge on the rail again and pointed it so I can watch it. When I turn the key to acc pos. it goes to @25 and nose dives. When I crank it goes to @20 and then slowly drops. If I toggle it between acc and crank the needle goes a tiny bit higher. So I bounced it up up up until @25 and then held it cranking and it started! I let it idle a while and tried it again and it seemed to be the same struggling but less toggling to get it up. But once it is started I get @35-37 psi. I wonder if I have the same prob. as you guys do or mine is different. I'll try starting it tomorrow and we'll see.
I got it started today but it seems to still have the problem. I put 5gal of gas with 3oz of stabil and also put the gauge on the rail again and pointed it so I can watch it. When I turn the key to acc pos. it goes to @25 and nose dives. When I crank it goes to @20 and then slowly drops. If I toggle it between acc and crank the needle goes a tiny bit higher. So I bounced it up up up until @25 and then held it cranking and it started! I let it idle a while and tried it again and it seemed to be the same struggling but less toggling to get it up. But once it is started I get @35-37 psi. I wonder if I have the same prob. as you guys do or mine is different. I'll try starting it tomorrow and we'll see.
loubotzz77
New member
Re: fuel pressure
sorry i havent gotten to u guys havent really did anything to the truck except body work ill keep u guys posted about the distributor and fule pressure problem
sorry i havent gotten to u guys havent really did anything to the truck except body work ill keep u guys posted about the distributor and fule pressure problem
Rexxenexx
Active member
Re: fuel pressure
Yea. I didn't use the pulsator on my racetronix install. It's just a small black hose w/ two clamps.
My Ty didn't start the next day. I pulled a plug and it look like it didn't fire so maybe my coil is crap or something. The battery check looked good I have to check out the cap,coil, and maybe starter tomorrow. I'm lucky I have a couple years supply of UR5's since the lady at pepboys decided to give me the box of UR5's instead of the six I ordered. I know cruel but they deserve it.
It IS normal when you turn the key (not all the way on) for the fuel pump to turn on for a short time right? That's just to pressurize. When you crank it and the engine is on the pump is fully on. So your guys prob is when the engine is fully on it takes a dump?
EDIT: I changed the plugs and wires (UR5's .035 + MSD wires) and still it didn't start. It only started when I jumped the fuel pump jumper and cranked it, even then it had a tough time and idled like crap for like 3-4 min. I ordered an MSD cap+rotor and coil from summit, only the plugs have been changed before today. The cap+rotor, coil, and wires are ancient. I did check the cap and rotor and they looked ok but I bought the MSD just for good measure. Maybe my starter is a POS and doesn't crank enough to get it going before the pressure goes down?
Yea. I didn't use the pulsator on my racetronix install. It's just a small black hose w/ two clamps.
My Ty didn't start the next day. I pulled a plug and it look like it didn't fire so maybe my coil is crap or something. The battery check looked good I have to check out the cap,coil, and maybe starter tomorrow. I'm lucky I have a couple years supply of UR5's since the lady at pepboys decided to give me the box of UR5's instead of the six I ordered. I know cruel but they deserve it.
It IS normal when you turn the key (not all the way on) for the fuel pump to turn on for a short time right? That's just to pressurize. When you crank it and the engine is on the pump is fully on. So your guys prob is when the engine is fully on it takes a dump?
EDIT: I changed the plugs and wires (UR5's .035 + MSD wires) and still it didn't start. It only started when I jumped the fuel pump jumper and cranked it, even then it had a tough time and idled like crap for like 3-4 min. I ordered an MSD cap+rotor and coil from summit, only the plugs have been changed before today. The cap+rotor, coil, and wires are ancient. I did check the cap and rotor and they looked ok but I bought the MSD just for good measure. Maybe my starter is a POS and doesn't crank enough to get it going before the pressure goes down?
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