toyvet1

Should a TPI engine die when the vacuum hose to the fuel regulator in disconnected?????

mrvette

YES!! the **** rate of the injectors is so high on account of fuel pressure being sky high....the a/fuel ratio is so upset it can't run....

GENE

BSeery

yeah -- it should flood to death. If not, it will run like crap.

If it keeps running it's possibly a sign of a weak pump or clogged injectors not giving enough fuel.

PatsLs1vette

actually guys when you take the vacuum line off the regulator all your doing is bumping the pressure up to 43 lbs.Vacuum line on is 36-38 lbs vacuum off 42-45 lbs or abouts,,especially when your using an adjustable regulator you have to have the vacuum off when your adjusting the pressure for wot.by disconnecting the vacuum to the regulator it should not stall the motor,your only running it at 43 lbs or so now.He could have a regulator problem hes gone to check the pressure first to see where its at now.


[Modified by patsnitrovette, 6:50 AM 6/27/2003]

mrvette

Pat, at idle it will kill my engnes every time....pull that line and it's flooded....

GENE

PatsLs1vette

really it shouldnt though,the fuel pump is putting out approximately 100lbs to the regulator then the regulator should regulate it down to 43-45 lbs without vacuum,when you put the vacuum to it it brings it down to 36-38 lbs,so at wide open throttle itll bring it back to 43-45 lbs.You can put an adjustable regulator on it and bump it to 50lbs and still run.Gene whats your fuel pressure at?


[Modified by patsnitrovette, 7:45 AM 6/27/2003]

toyvet1

I got the fuel pressure checked this morning. At idle 36psi @17 " vacuum. Rev the engine and the vacuum slowly drops but fuel pressure stays steady at 36 psi. Vacuum dropped to 10" and fuel presseure stayed at 36. Would that indicate a bad regulator? :banghead: :banghead: :banghead:

PatsLs1vette

when you snap the gas it should go up to 42-45 lbs.if you slowely move the throttle up it would still have vacuum to it then it wouldnt rise up,you have to snap the throttle hard and see if it goes up,like if your gone to go wide open throttle.

toyvet1

no reponse if you crack the throttle 36 psi

Budman68

Sounds like a bad reg to me or a vacuum leak. Are you running a T at the regulator? Or another location?

mrvette

Pat, MY pressure is set lo....39 with NO vacuum, and ~35--as I recall---when idle.....

I also know, if engine is still, and pump wired on, pressure will be 40+ a smidge and IF I take pliars and temporarily pinch the RETURN line to the tank this is the one after the regulator...that will increase the fuel pressure quickly to about 60 psi which is max I seem to get....which is fine for just a battery and jumper wire on the pump hot wire....so the thing hits ~60 some off psi....

NOW, release that line quickly after the pump peaks out, and you will hear a vibration coming from the regulator, as the pressure is released and it's back in operation...what this does is unseat that regulator as far as it can go...and that frees up any crap built up in the regulator which may be keeping it open enough...so it stays a say 36 or whatever, and never actually increases pressure like when the throttle is cracked....try stall checking the engine or running car with heavy throttle take off, watch the gauge, it must increase to 40++ psi...if not, your regulator got dirt in it, not closing...so you need clear by pinching and releasing that return line....

GENE

PatsLs1vette

yeah sounds like regulator trouble to me too,gene if i pinch return off i can max out at 100 ,itll idle at 38 and snap throttle ill get 43.what pumps are you guys running?im running a 89 vette pump intank,i removed my inline pump.


[Modified by patsnitrovette, 12:30 PM 6/27/2003]

Budman68

I'm running a late model Camaro pump.

mrvette

I"mrunning a universal frame mounted pump, with a stock '72 pickup arrangement, throug the FI filter, into the pump...yeh filter on suction side...and then into the stock line forward...3/8 then the return line back to the tank....stock 1/4 inch....
NOW wit the stock engine L48 rebuilt, and the original chip, I had NO surging or irregular acceleration....
NOW, when hot I do...wonder what's going on??? been tempted to try a larger return line, but haven't bothered yet...

GENE

toyvet1

Hey guys thanks for the help. Over the weekend I replaced the fuel regulator and a tune up including new fuel filter. Now when the throttle is snapped I get a quick jump in fuel pressure. The car runs better than it ever has, it finally has some stones... :cheers: :cheers: :cheers:

Fevre

Gene

Do you have the vapor return line open (avail for use)? I believe that one is larger than the fuel return line.

mrvette

Yes, I have that cannister line available, but it's in that situation there with the charcoal, and the check valve, and I haven't played with it yet....
it seems to run fine for the most part, so I"m not all that concerned...maybe some day when I think of it....you know, one of them buttons with '

Round Tu-It lettered on it....

GENE