adjustable fuel pressure

[imdawrlus]

i have an 89 1500 350 fuel injected.....i want to put in an adjustable fuel pressure regulator....i want to get the type where you block off the stock regulator and tie in the new regulator in the return line....its 3/8 inch fuel line if that matters...where can i get a regulator??? links would help a lot! thanks...

[imdawrlus]

nothing???

[T Man]

the only one that I have seen for a TBI replaced your stock fpr. ill look for one if someone cant post one before me

[imdawrlus]

would something like this work? (http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=3432&prmenbr=361)

how is it adjustable??

[T Man]

Yup, that is pretty close it what I was thinking of. The way it works, is there is a spring that places pressure on a diaphragm, in the middle of the diaphragm is a small steel blockoff on an oriface of the top of the injector pod piece. The more pressure on the diaphragm, the harder it is for the fuel to get through the oraface. The less pressure, the easier, see how that works? The adjustable fpr that I was thinking of has a long bolt coming out of the bottom with a knob on the head.

http://members.shaw.ca/betterthanyoutoo/how-to/fpr/fpr.htm

[Matt 4.3 TBI]

TMan found the link I was looking for that uses the external regulator. Turbo City made a kit with an adjustable regulator you bolt in place of the stock unit. It has a bolt with thumbscrew that sticks through the bottom of the TBI base, so you can reach behind the TBI unit and turn it to adjust fuel pressure without needing any tools.

I had some pics of mine, but I can't get to them from work. I'll post them up later, but here's a link to the site that sells them. http://www.cfm-tech.com/catalog/fuel_-_cfm-tech_adjustable_fuel_pressure_regulator_for_gm_tbi _549435.htm

[imdawrlus]

i have an adjustable fpr on it right now that i made....i followed the directions and had the nut welded on there and everything......the problem is that the bolt is too short and it bottoms out and i cant add any more pressure......i could take it apart and fix it but thats a major pita....plus i'm using and old diaphram so i dont how much longer thats gonna last.....i would much rather spend a little money and do it right.....matt, does that fpr come with a diaphram and spring? if not i'll probably look into something like THIS (http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=4354&prmenbr=361)

[Matt 4.3 TBI]

You use the stock spring with that regulator, and the diaphragm is only around $7 at AutoZone. There are stronger springs you can get, but I'd be wondering if your fuel pump isn't getting weak if it isn't pushing enough with it cranked all the way down.

[T Man]

There is a guy, goes by "Betterthanyou" over at .org who is running one of the external pressure regulators on his 3.4; camaro motor. Seems to like it. Hit him up

[imdawrlus]

There is a guy, goes by "Betterthanyou" over at .org who is running one of the external pressure regulators on his 3.4; camaro motor. Seems to like it. Hit him up

what site is he on?

There are stronger springs you can get, but I'd be wondering if your fuel pump isn't getting weak if it isn't pushing enough with it cranked all the way down.

the spring isnt compressed all the way...when i was making it i made the threaded rod too short now theres not much left to turn...

if i did buy one of the regulators that bolts in place of the stock regulator i still need to buy the diaphram which only comes in a kit at autozone for 35 bucks.....i would want a new spring and i can only get that at the dealer....so if i bought the stock replacement its going to turn out to be just as much as if i bought the external regulator.....i'm still thinking about all the options tho...

[Matt 4.3 TBI]

I know they sell the regulator diaphragm with just a fuel meter cover and fuel outlet gaskets. Don't ask for the TBI rebuild kit, that's the $40 box with everything.

[imdawrlus]

ya i've bought the regulator kit before....it comes with the fuel meter gasket, diaphram, return passage gasket, and special studs to line up the fpr housing with the meter cover.....i'm posative it wasent any less than 30 bucks...

[T Man]

the full rebuild kit costs about 45 dollars. I bought about 4 of them last winter.

[Maximus]

For the price of a in line adjustable regulator is gonna cost you,you could buy the turbo city one for less money or just make another one from a stock unit and save cash.But im with Matt I think you might have a fuel delivery problem to the regulator like a filter or a lazy pump.

[imdawrlus]

i'm starting to think its not the regulator anymore....the filter is new.....the gas tank is also new but the pump is not...i'm the fourth owner so it might have been replaced somewhere along the line but i'm not sure.....do you think its an engine electrical problem or a fuel system problem?? i thought pumps either work or dont work....nothing in between....i can get a new fuel pump for 40 bucks and i can have it in there in a couple hours....i just dont want to throw away money and time....

[Sparky2263]

You're trying to fix a driveability problem? And you think it may be fuel related? First thing, fuel pressure and volume test. Period.

[imdawrlus]

haha ok ok....i'll get a pressure tester.....if its where its supposed to be what does it mean? what if its too low, what does that mean?

[Matt 4.3 TBI]

If the pressure's right, and you have that regulator cranked down, I would suspect a restriction in the fuel system like a bent line, clogged filter, or clogged fuel pump sock.

If it's low, I would say the fuel pump is on it's way out, but could also be a restriction.

[Sparky2263]

haha ok ok....i'll get a pressure tester.....if its where its supposed to be what does it mean? what if its too low, what does that mean?

What particular driveability problem are you having?

[imdawrlus]

rough idle and lack of power...the things like a dog....i almost have to downshift to make it up small inclines......

[Sparky2263]

Then fuel system testing is definitely called for.

[Matt 4.3 TBI]

Also keep in mind if you're running too rich you'll lose power and have a poor idle as well. Adding fuel might be part of the problem here. Let us know what numbers you get from the fuel pressure gauge and we'll go from there.

[Sparky2263]

Matt is on top of things, as usual.............

:)

[imdawrlus]

i think u guys are right about the problem NOT being the fpr.....since i've installed it i've had to crank it up more and more just to keep it drivable....its slowly gotten "worse"...that makes me think that its something in the tank or the pump......i have a full tank right now so i'm going to wait before i dig into it.....how much do u think a garage would charge to test fuel pressure? or where can i get a gague?

[Matt 4.3 TBI]

You can pick up an Actron TBI gauge kit from AutoZone. It has a t-fitting that you put between the tank and fuel filter, and screw the gauge onto that. Runs about $40.

[imdawrlus]

ok i checked the pressure and it runs a steady constant 15 psi....i have a couple rubber hoses and i squeezed the pressure line before the gague and brought the pressure down to 10 psi and it died.....the needle has a very very slight twich, about a half a psi....the gague is installed on the outlet side of the filter....whats the next step??

[Matt 4.3 TBI]

15 psi is too high for a generally-stock TBI system. Operating level is 9-13 psi, and 13 will be bordering on rich. Try lowering the pressure to around 12 psi, disconnect the battery for a few minutes to clear the short-term fuel maps in the ECM, then drive it and see how it acts.

[imdawrlus]

if 15 is too high and its making it run rich then why do i still get a code 44? i'm going to go out right now and turn down the pressure....i'll let u know how it goes......

[imdawrlus]

ok so i went out and started loostening the bolt to the fpr....i unloosened it half way and start it and look at the gague...its at about 14 psi.....the truck is running like $hit and the idle sucks.......so i go back under the hood and start to loosten it somemore........i keep going until its allmost all the way out....its just under 14 psi.....so loosten it all the way....about 13.5 psi and i thought the truck was going to stall.......i put everything back together and take it for a ride....i'm not sure if it got worse but i KNOW it didnt get better.....i need the truck for work tomorow so i'm going to go out and put everything back together right now....unless i got a bad gague all this dosent make any sence to me....why would it run lean with so much fuel pressure?? and why wouldent the fuel pressure go down when i loostened the bolt??...let me know what u think...

[Matt 4.3 TBI]

When I was still using my adjustable regulator, I had a problem with it running too rich. I loosened the bolt all the way, to the point it was completely removed, and it was still at 14psi. The problem ended up being the regulator diaphragm. I had replaced it, but it made no difference. Turns out the replacement was bad as well. The next replacement fixed it. That was a major headache, as I couldn't start rebuilding the engine until the fuel pressure issue was worked out.

I'm curious if the O2 sensor is reading accurately as well. With 15psi you should be able to smell some unburned fuel in the exhaust.

[imdawrlus]

i dont know if u remember or not but i went through this whole thing a couple months ago....i tried 2 or 3 different diaphrams and it still ran like crap....the only thing that made it better was the adj fpr that i made.....now it seems to have gotten worse, the things a dog.....now i want to fix it right......i tried checking for vacuum leaks and i couldend find anything.....i've had 2 o2 sensors in it and it made no difference...i still have the old one so i'm thinking of putting it in to see if it makes a difference......i really want to get this sorted out because its becoming a pain in the azz....i almost wish i never sold my s10........

[imdawrlus]

any thoughts?

[Matt 4.3 TBI]

I was waiting on more data, thought you were going to double-check it with another O2 sensor. If the diaphragm is good, and the O2 is accurate, then the only parts left in the equation are the fuel pump and injectors. Have you checked the spray pattern on your injectors? Take the air filter off while it's running and watch the fuel spray. It should be a cone-pattern. If it's dribbling or not spraying a nice cone shape, the injectors could be dirty, or at least the injector filters may be clogged.

[Matt 4.3 TBI]

Almost forgot, if you've got a timing light, you can hook it up to the #1 plug wire and aim it down the throttle bores, you'll see the fuel in mid-air when the light flashes. Open the throttle just a bit and watch for the fuel to move up and down the bore. Switch the pickup to the #2 wire and check the other injector the same way.

[imdawrlus]

the fuel spray is good.....when i look down the tb i see a fine "mist"...i have used a timing light before but i was told to hook it up to the coil wire....still, a fine mist....the filters on the injectors are new.....i have a spare set of injectors that i've had in there and it made no difference....

[imdawrlus]

i think i'm going to just leave it alone and drive it....the more and more i think about it the more and more i dont want to spend time and money on it.....it runs decent, not perfect but decent, drives smooth....and does extreemly well on gas...i havent got gas since a week ago yesterday and i still have a half a tank...i've used it every day this week....the good mileage is probably because of it running lean....

when i think of putting money into this it just reminds me of how much i put into my s10....when i sold it i got NOTHING back.....so why bother? if it aint "broke", dont fix it.

[imdawrlus]

one thing that i have noticed is that is it fast as hell in the morning when the engine is cold....great throttle response and acceleration....i had the timing advanced quiet a bit and i had a little ping under load so i went and took out a little bit of timing and it seemed to make it a little better when its warmed up.....why would it have more power cold??

[Sparky2263]

hmmmm, either it likes it rich or your coolant temp sensor is awry. Got a scanner?

[imdawrlus]

when you say scanner do you mean a multimeter? because i dont have one haha.....the previous owner put in a new coolant temp sensor but that dosent mean its not broken....he also had a 180 stat in it.....a couple weeks after i got it i put in a 195 stat.....i remember it having way more power when i first got it....

[imdawrlus]

well i put my spare coolant temp sensor today and it made no difference at all.....so i put the old one back in.....