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Super High fuel pressure after putting on new Fuel Pump, regulator and relay


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r2424243
New User

Mar 14, 2020, 8:08 PM

Post #1 of 11 (488 views)
  post locked   Super High fuel pressure after putting on new Fuel Pump, regulator and relay  

I have a 84 c 20 with a 454bbc. Fuel pump went out so I changed fuel filter, pump, relay and regualtor. Pump rated 7-9psi but pressure is pegged at 14. I thought I got a faulty regulator so I bought a new one, the same thing is happening. I don't see any bent lines or anything that could be causing this. It's got an edlebrock carb. dual tanks. Any thoughts what's causing extreme fuel pressure?Mad


Hammer Time
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Mar 15, 2020, 3:50 AM

Post #2 of 11 (474 views)
  post locked   Re: Super High fuel pressure after putting on new Fuel Pump, regulator and relay  

How are you testing this? Make sure you are "T-ing" into the line and not "dead heading". Also make sure your gauge is accurate.

If the regulator is good, about the only thing that could cause that is a restricted return line. You might try disconnecting that line and letting it feed into a can and see if that changes anything.

Also make sure you put the correct fuel pump in it and didn't get one for a Vortec engine. They run over 60PSI.



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(This post was edited by Hammer Time on Mar 15, 2020, 3:52 AM)


Tom Greenleaf
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Mar 15, 2020, 5:43 AM

Post #3 of 11 (464 views)
  post locked   Re: Super High fuel pressure after putting on new Fuel Pump, regulator and relay  

? Seems all altered and admit IDK how dual tanks were done. One fuel pump and switch which it draws from or a pump at or in each tank? Carb changed could change pressure spec and near certain defeated a ton of emission things controlled by vacuum is all doable but how documented if anything were the changes?


This was almost certainly a 4V Quadrajet even GM couldn't adjust one new (Rochester Division) so were tossed for others TMK Edelbrock never made anything for an OE vehicle a huge "who knows what the heck it's good for" to me IMO.


People do, did and got away with good running vehicles by now how done is probably all "Frankensteined" up need to find some info on just what you wish to do??


T



Hammer Time
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Mar 15, 2020, 6:17 AM

Post #4 of 11 (460 views)
  post locked   Re: Super High fuel pressure after putting on new Fuel Pump, regulator and relay  

This has nothing to do with carbs. It's a factory TBI system.



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Tom Greenleaf
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Mar 15, 2020, 6:36 AM

Post #5 of 11 (456 views)
  post locked   Re: Super High fuel pressure after putting on new Fuel Pump, regulator and relay  

Quote top post ">It's got an edlebrock carb. dual tanks. Any thoughts what's causing extreme fuel pressure?Mad<
IDK is this computer that screwed up - mine? Carbs in general would run well at 4-6 PSI if higher just as long as needle valve was set for it deal with it. If Edelbrock made a TBI (carb looking) thing IDK. It is mentioning electric I only know of ONE carbed (OMG a Chevy Vega) vehicle with an electric pump so what do we have to work with?


I have seen many folks put in-line electric pumps instead of especially the pest GM block mounted ones with pushrods this would have. Those stated right on the pump what pressure they could/would do I have one as a fuel mover thing right now,


Tom



Hammer Time
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Mar 15, 2020, 6:45 AM

Post #6 of 11 (454 views)
  post locked   Re: Super High fuel pressure after putting on new Fuel Pump, regulator and relay  

Sorry, I missed that. You are right.

He quoted the fuel pressure spec for TBI, even 9-13 is too much for a carb. No wonder he is having problems.

It sounds like he has tried to convert a return type system into a returnless system. That's not going to work.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
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Mar 15, 2020, 7:01 AM

Post #7 of 11 (450 views)
  post locked   Re: Super High fuel pressure after putting on new Fuel Pump, regulator and relay  

People get confused what they are - we know that too. 1983 was all carbs and 1985 was almost all TBI. OMG what was in 1984? I owned an S-10 was a carb next year TBI not full size so IDK all of them.
OK: I've seen and own in-line fuel pump like a larger fuel filter with a mounting strap some folks didn't want to take tanks out or instant fuel pressure for a carb before it even starts.
Back? Edelbrock carb? Could that have a different spec? Could this just be the wrong pump? Any or All of the above IMO, Tom


Hammer Time
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Mar 15, 2020, 7:10 AM

Post #8 of 11 (448 views)
  post locked   Re: Super High fuel pressure after putting on new Fuel Pump, regulator and relay  

I don't know if this guy is ever going to respond but he has removed the throttle body and dropped a carb there. He still has the TBI delivery system with an in-tank pump and that simply isn't going to work unless he finds a way to let the excess fuel bypass back to the tank and he finds a bypass regulator that drops the pressure down to 3-5 PSI.

What he has done ends up being totally illegal by Federal law. His computer and 0/2 sensors are worthless now.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on Mar 15, 2020, 7:12 AM)


Tom Greenleaf
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Mar 15, 2020, 7:41 AM

Post #9 of 11 (440 views)
  post locked   Re: Super High fuel pressure after putting on new Fuel Pump, regulator and relay  

I'm sure we've scared OP away. I/we tried. Agree it was a cobbled TBI to maybe a real carb again. Too bad you can choose volume, pressure just add power and ground forget all the rest it's a diaphragm type so self regulates AND can run dry! Mount where fuel filter is on frame rail types add a real one before it and be done using existing power that's relay or fused in some way?
Legal? IMO 1983 is the year you can play and older. About now who cares for a truck? Can work with the things a hay wagon or whatever. ALL sheet metal available, adaptors pre made for another engine size the list is endless.
If unrusted an easier build what you want from the frame the 454 was used in tons of things other than cars/trucks also. Laugh, the most I knew were in super hog yachts, two hogs but tons of power and needed it. Ooooh - understand counter rotating engines too can't have both spin the same way truck are backwards the cars were not could use car parts or truck for many things.
The skinny whatever this creation it just takes the right base understanding if only pressure the problem and really too high it's the wrong pump get another they can be self regulated by spring not another device so by-pass the horrors.


I need to go get gas today before this crazy virus hysteria folks discover that gas kills germs there will be a rush on it for that! Joking if anyone reading that!


OP - This can be fixed at the age you really just need an old phart be done with this is no time with the correct pressure and move on none of us know just what you have is the whole problem,


Tom
(edit to say fuel filter to rail not at carb)



(This post was edited by Tom Greenleaf on Mar 15, 2020, 7:45 AM)


Ramntm
User

Mar 25, 2020, 5:00 PM

Post #10 of 11 (235 views)
  post locked   Re: Super High fuel pressure after putting on new Fuel Pump, regulator and relay  

I ran into the exact same problem on a restored 1967 El Camino about 5 months ago. The original fuel pump was leaking fuel, but the engine ran perfectly. I replaced the fuel pump, and after running about 3 minutes, it would start dumping fuel from the vent on the Carburetor and flooding. I checked the fuel pressure, and it was running 14 pounds of fuel pressure, when it should have no more than about 6 pounds. I removed the fuel pump and compared the "pump lever" to the original pump. The lever was different than the original, so I sent the old fuel pump to the parts supplier to match up the new pump to the original. Problem solved. 6 Pounds of pressure, and it ran properly again.


Hammer Time
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Mar 25, 2020, 6:39 PM

Post #11 of 11 (229 views)
  post locked   Re: Super High fuel pressure after putting on new Fuel Pump, regulator and relay  

Well, except in this case it had an electric fuel pump in the tank with fuel injection and now it has a carb so no mechanical pump at all.

The original poster hasn't responded since his original post so there is no point in this going any further.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.







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