Cosworth Starving for Fuel

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Cosworth Starving for Fuel

Postby Biscayne John » Fri Dec 28, 2012 1:25 am

Hello,
This is my first post here and I'm sure many will come. I bought a 1975 Cosworth this past Labor Day. I am the second owner with a GREAT paper trail! It was well maintained has about 75K and was not on the road since 1997. I got it running and on the road, runs very good, besides some clutch issues really not much to complain about, except.......

Here is my problem and or question
On my first test drive after driving it 10 minutes or so I had shut it off, when I went to start it back up, it would start run and stall, gave the exact feeling of a car running out of gas, then it started and was fine. A few starts later same thing again, then like magic it started.

Then it ran fine for a couple of short trips next few days, then again, I was on the road an had my "road tool bag" with me. For some reason I saw a surgical clamp and I don't know why I did but I placed it on the return line of the fuel pressure regualtor and it started right up. With the purchase of the car a NOS fuel pressure regulator came along with it (as well as every other sensor, I know big time score!) Replaced it problem went away for a few days then back again, put the original back started right up, then it happened again. Sandy came lost power, went to Florida after the storm on business 6 weeks later I return drive the car no problem.

I have not placed a gauge on either side yet, only happens when it has been running, original fuel pum was replaced with a Porche pump by original owners son. I replaced the pump in tank with a Fierro pump (tank was spotless inside), filter was replaced. Cold Start valve is bypassed by me, it was leaking and was running a 3600 RPM when it was hooked up. The intermitent part is what is getting to me......... :bang: Ideas?????

How does the regulator work the higher engine vacume the valve opens or closes?
Thanks
John Mahoney
Long Island NY/Ocala FL
AACA
VCCA
CVOA
BCA
The Fleet
1954 Chevrolet BelAir sPort Coupe
1960 Chevrolet Impala 2 door Sport Coupe 348/340HP (AACA Grand National Winner)
1962 Chevrolet Impala 2 door Sport Coupe 409/409HP(the last one to do)
1962 Chevrolet Biscayne 2 door Sedan 327 Auto (AACA Grand National Winner)
1977 Monza Mirage 4 speed
1988 Celebrity Wagon (was my mother in laws since new 42K miles)
2011 28' Bendron Titan Enclosed Trailer; what they travel in when we go
2018 GMC 2500 Sierra Diesel Crew Cab; how we get them there without sweating
2015 Cadillac CTS
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Re: Cosworth Starving for Fuel

Postby cosvega76 » Fri Dec 28, 2012 10:06 am

Welcome, John!

There is a wealth of information here, and a lot of friendly folks. For more detailed Cosworth Vega information, you may also want to check out the Group on Yahoo Autos: http://autos.groups.yahoo.com/group/cosworthvegas/ And if you haven't already, I would also suggest to join the Cosworth Vega Owners Association. Go to http://www.cosworthvega.com/ for more information.

More vacuum on a fuel pressure regulator will decrease the pressure - in other words, allow more fuel to return to the tank - since the engine is seeing a reduced load. Naturally, when the engine is under load, the vacuum decreases, requiring more fuel. A CV requires around 44 psi for the injection system to operate properly, and may increase to around 50 psi under load.

Probably the best answer I can give is to attach a fuel pressure gauge and mount it where you can see it. Even a test gauge taped to the windshield will work. Then you can see what happens to the pressure when it stalls.

One thing you may want to check, since the only pump you have is in the tank, is the connections of the conductors at the "hat" of the sender/pump unit to the pins where it connects to the external plug connector. The factory uses only push-on clips to hole the conductors to the pins, and they may be loose or not making a clean connection. Of course, that would mean dropping the tank, so you may want to continue with your diagnosis first.


Chuck
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Re: Cosworth Starving for Fuel

Postby hammerdown7 » Fri Dec 28, 2012 11:01 am

Welcome John,

Good suggestions from Chuck. I have a couple questions. Are you still using the Porsche pump and is the Fiero pump for a 4 cyl or for the V6? Chuck and others have used the V6 pump which would normally eliminate the high pressure pump. I agree with Chuck that knowing what is happening to the fuel pressure is the best place to start the diagnosis. This site has a lot of information on a variety of h-body cars but there are not many Cosworth specific owners here, the Yahoo site is best for trouble shooting Cosworth engine questions. Even though I have owned Cosworths since 1978 almost all of mine have been carburated so, unfortunately, I'm not able to help much with the EFI.

Dick
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Re: Cosworth Starving for Fuel

Postby Biscayne John » Fri Dec 28, 2012 11:51 am

I have the info for the tank pump in the shop which I be in later today. I also have a lead on an original rebuilt pump up in the Bronx about 25 miles away which is on the agenda for today. Looks like I need to have three gauges in position and hope for the problem to replicate. One on the regulator coming from the rail, one after the regulator on the return and one from the tank to the LP pump and HP pump?
Thanks
John Mahoney
Long Island NY/Ocala FL
AACA
VCCA
CVOA
BCA
The Fleet
1954 Chevrolet BelAir sPort Coupe
1960 Chevrolet Impala 2 door Sport Coupe 348/340HP (AACA Grand National Winner)
1962 Chevrolet Impala 2 door Sport Coupe 409/409HP(the last one to do)
1962 Chevrolet Biscayne 2 door Sedan 327 Auto (AACA Grand National Winner)
1977 Monza Mirage 4 speed
1988 Celebrity Wagon (was my mother in laws since new 42K miles)
2011 28' Bendron Titan Enclosed Trailer; what they travel in when we go
2018 GMC 2500 Sierra Diesel Crew Cab; how we get them there without sweating
2015 Cadillac CTS
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Re: Cosworth Starving for Fuel

Postby cosvega76 » Sat Dec 29, 2012 8:18 am

John,

Does the car have only the Fiero pump in the tank, or is the OE high pressure pump still installed under the rear seat floor?

Either way, I would start with just a pressure gauge monitoring the pressure at the fuel rail, before the regulator.


Chuck
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Re: Cosworth Starving for Fuel

Postby hammerdown7 » Thu Jan 10, 2013 9:17 am

John,
Any updates?
Dick
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Re: Cosworth Starving for Fuel

Postby Biscayne John » Thu Jan 10, 2013 11:50 am

I just got in the door from some surgury on my knee. I took it out over the weekend everything went real good, I loaded it in the trailer and and I am going ot take it down to Florida for a few weeks and look at it down there. The 80+ degree temps are inviting. I did pick up a rebuilt electric pump from Rich Bastardi, his shop is about 1 miles from where I grew up in the Bronx. I'll give you an update once I get down there, this knee problem really hurt my movement, plus I have a lift down there
Thanks
John Mahoney
Long Island NY/Ocala FL
AACA
VCCA
CVOA
BCA
The Fleet
1954 Chevrolet BelAir sPort Coupe
1960 Chevrolet Impala 2 door Sport Coupe 348/340HP (AACA Grand National Winner)
1962 Chevrolet Impala 2 door Sport Coupe 409/409HP(the last one to do)
1962 Chevrolet Biscayne 2 door Sedan 327 Auto (AACA Grand National Winner)
1977 Monza Mirage 4 speed
1988 Celebrity Wagon (was my mother in laws since new 42K miles)
2011 28' Bendron Titan Enclosed Trailer; what they travel in when we go
2018 GMC 2500 Sierra Diesel Crew Cab; how we get them there without sweating
2015 Cadillac CTS
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Re: Cosworth Starving for Fuel

Postby hammerdown7 » Thu Jan 10, 2013 11:56 am

Enjoy the warmth, I'm in Michigan! Get well soon.

Dick
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Re: Cosworth Starving for Fuel

Postby cozwurth » Fri Feb 15, 2013 11:24 pm

IIRC the ECM controls the fuel pumps, and the relays or contacts going bad was fairly common. My second CV had the fuel pumps set on a manual switch because of that same problem. There was someone in the CVOA who could fix this problem, along with any others in the ECM, but it has been a few years since I've had any dealings anything CV. You only need one pressure gauge at the fuel rail like cosvega76 said. I don't remember which ECM plug it is, but you should be able to back probe the fuel pump leads to check for voltage if and when you see the fuel pressure drop.
Dave
And ye shall hear of wars and rumors of wars; see that you are not troubled: for all these things must come to pass, but the end is not yet. For nation shall rise up against nation, and kingdom against kingdom: and there shall be famines, and pestilences, and earthquakes in diverse places. All these are the beginnings of sorrows. MATT 24:6-8
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Re: Cosworth Starving for Fuel

Postby Biscayne John » Fri Feb 22, 2013 12:59 am

UPDATE!!!!!!!!!!!!!!!!!!!!!!!!!!

OK here we go. I placed a fuel pressure gauge I am getting 30 pounds, (I know it's low) when I crimped the return line it jumped to 60 and ran great. Replaced all of the rubber hoses, still the same. Replaced the porsche pump (HP) with a NO$ GM pump, still the same, replaced that set up with a V-6 camaro in tank set up as was recomended STILL THE SAME, now when I crimp the line and give it throttle it breaks up between 2,500 and 3,500. But at least now it's consistant. I realize now it can't be the pump because it would have never gone to 50-60 pounds when I crimped it. I replaced the pressure control valve with 4 different ones.......... same.................... I am at a loss. I replaced the filter with a new Bendex unit. There is not one part of the fuel system that I did not touch, new injector O rings, I also hold pressure when shut down. need help!!!!!
John Mahoney
Long Island NY/Ocala FL
AACA
VCCA
CVOA
BCA
The Fleet
1954 Chevrolet BelAir sPort Coupe
1960 Chevrolet Impala 2 door Sport Coupe 348/340HP (AACA Grand National Winner)
1962 Chevrolet Impala 2 door Sport Coupe 409/409HP(the last one to do)
1962 Chevrolet Biscayne 2 door Sedan 327 Auto (AACA Grand National Winner)
1977 Monza Mirage 4 speed
1988 Celebrity Wagon (was my mother in laws since new 42K miles)
2011 28' Bendron Titan Enclosed Trailer; what they travel in when we go
2018 GMC 2500 Sierra Diesel Crew Cab; how we get them there without sweating
2015 Cadillac CTS
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Re: Cosworth Starving for Fuel

Postby hammerdown7 » Fri Feb 22, 2013 3:25 pm

John,
There are not many Cosworth folks on this board. I have run Webers for a very long time so I can't be much help either. I'm going to suggest you go to Yahoo Groups and, unfortunately, you will have to explain your problems again from the beginning so everyone understands. Here's the link, http://autos.groups.yahoo.com/group/cosworthvegas/
Lot's of experience there.
Dick
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Re: Cosworth Starving for Fuel

Postby cozwurth » Fri Feb 22, 2013 10:29 pm

It still sounds like a pressure regulator problem. IIRC the pressure should be around 42 PSI, and rise when vacuum drops. The yahoo group that Dick linked to has the fuel injection manual posted online, so you can look through that once you join there. Look in the "files" section.
Dave
And ye shall hear of wars and rumors of wars; see that you are not troubled: for all these things must come to pass, but the end is not yet. For nation shall rise up against nation, and kingdom against kingdom: and there shall be famines, and pestilences, and earthquakes in diverse places. All these are the beginnings of sorrows. MATT 24:6-8
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Re: Cosworth Starving for Fuel

Postby Biscayne John » Sat Mar 16, 2013 2:45 pm

Update: I picked up a weber set-up. I want to drive it and get home under it's own power
John Mahoney
Long Island NY/Ocala FL
AACA
VCCA
CVOA
BCA
The Fleet
1954 Chevrolet BelAir sPort Coupe
1960 Chevrolet Impala 2 door Sport Coupe 348/340HP (AACA Grand National Winner)
1962 Chevrolet Impala 2 door Sport Coupe 409/409HP(the last one to do)
1962 Chevrolet Biscayne 2 door Sedan 327 Auto (AACA Grand National Winner)
1977 Monza Mirage 4 speed
1988 Celebrity Wagon (was my mother in laws since new 42K miles)
2011 28' Bendron Titan Enclosed Trailer; what they travel in when we go
2018 GMC 2500 Sierra Diesel Crew Cab; how we get them there without sweating
2015 Cadillac CTS
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Biscayne John
 
Posts: 475
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Re: Cosworth Starving for Fuel

Postby Biscayne John » Sun Apr 21, 2013 9:11 pm

UPDATE:
ran it today with the webers on WOW I like it! Nice feeling now knowing I will get home under my own power
John Mahoney
Long Island NY/Ocala FL
AACA
VCCA
CVOA
BCA
The Fleet
1954 Chevrolet BelAir sPort Coupe
1960 Chevrolet Impala 2 door Sport Coupe 348/340HP (AACA Grand National Winner)
1962 Chevrolet Impala 2 door Sport Coupe 409/409HP(the last one to do)
1962 Chevrolet Biscayne 2 door Sedan 327 Auto (AACA Grand National Winner)
1977 Monza Mirage 4 speed
1988 Celebrity Wagon (was my mother in laws since new 42K miles)
2011 28' Bendron Titan Enclosed Trailer; what they travel in when we go
2018 GMC 2500 Sierra Diesel Crew Cab; how we get them there without sweating
2015 Cadillac CTS
User avatar
Biscayne John
 
Posts: 475
Joined: Thu Dec 27, 2012 7:29 pm

Re: Cosworth Starving for Fuel

Postby firebird77clone » Sat May 04, 2013 2:14 pm

I just skimmed the thread. The pressure regulator is vacuum controlled?

Put a vacuum guage on the control line, and a pressure guage on the outlet.


Crimping the return line and getting full pressure confirms the pump, and indicates trouble with the regulator. Having changed the regulator, it indicates control vacuum. Disconnecting vacuum line should cause pressure to spike.

Sounds like the Weber set up tolerates the low pressure better.
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