Author Topic: Problem with 850 DP Holley  (Read 793 times)

Offline jhaag

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Re: Problem with 850 DP Holley
« Reply #105 on: July 10, 2019 - 09:40:41 pm »
So let me see if I have this right. You had what you originally described as a small off idle bog, or lean condition per your air fuel gauge, Correct? Now you are chasing what you think is a fuel pressure problem? I don't follow. A fuel pressure/delivery issue will not show up until you put the engine under load. Does it accelerate once you get by the "bog/lean spot"? Is it running out of fuel at high rpm? Is the car still running alright except the slight "bog" you originally described? Just got to wonder why fuel cells and fuel lines that worked for 20 years all of the sudden don't?...   
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Offline cudabob496

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Re: Problem with 850 DP Holley
« Reply #106 on: July 10, 2019 - 10:44:07 pm »
So let me see if I have this right. You had what you originally described as a small off idle bog, or lean condition per your air fuel gauge, Correct? Now you are chasing what you think is a fuel pressure problem? I don't follow. A fuel pressure/delivery issue will not show up until you put the engine under load. Does it accelerate once you get by the "bog/lean spot"? Is it running out of fuel at high rpm? Is the car still running alright except the slight "bog" you originally described? Just got to wonder why fuel cells and fuel lines that worked for 20 years all of the sudden don't?...

for last 6 months fuel pressure has been slowly decreasing from 5.5 to 4.0. So, have been investigating every
possibility. Also, when pressure went below 5, started getting a spike is AFR up to 18 when crusing, or lately
when starting up and at idle. Was told an 850 DP below 5.0 fuel pressure might show the AFR spikes.

72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

2011 Kawasaki Z1000

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Re: Problem with 850 DP Holley
« Reply #107 on: July 10, 2019 - 11:41:57 pm »
You may be conflating 2 different issues. As to the fuel pressure, you have cleaned or changed almost everything without a change in pressure. I would change the gauge to start with.
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05 Hemi Durango, 01 Ram 4x4, 14 Ram 2500 4X4, 10 PCP Challenger 6 spd RT, 01 Viper GTS ACR, 52 B3B w/330 Desoto Hemi, 70 Hemi RR (under const)
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Offline cudabob496

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Re: Problem with 850 DP Holley
« Reply #108 on: July 11, 2019 - 01:26:58 am »
You may be conflating 2 different issues. As to the fuel pressure, you have cleaned or changed almost everything without a change in pressure. I would change the gauge to start with.

Its electric, I changed the sending unit. Yes, two issues, but they both occurred at the same time, and its
logical that low fuel pressure could cause a high AFR.
« Last Edit: July 11, 2019 - 01:53:27 am by cudabob496 »
72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

2011 Kawasaki Z1000

Online 70chall440

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Re: Problem with 850 DP Holley
« Reply #109 on: July 11, 2019 - 12:05:04 pm »
I completely agree that they appear connected, however its possible that they are not. That said, since you know what the fuel pressure is supposed to be, I would fix this first and see what happens after that. So, on that regard, remove your regulator and plumb the fuel pump straight to the carb and see what the pressure is.
Current Mopar
70 Challenger RT 440-6 EFI, 73 Cuda 416-6 EFI
05 Hemi Durango, 01 Ram 4x4, 14 Ram 2500 4X4, 10 PCP Challenger 6 spd RT, 01 Viper GTS ACR, 52 B3B w/330 Desoto Hemi, 70 Hemi RR (under const)
Past Mopars
9 x Challengers. AAR Cuda, 4 RR, 2 GTX, 4 Chargers, etc... (too many to list)

Offline cudabob496

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Re: Problem with 850 DP Holley
« Reply #110 on: July 11, 2019 - 12:48:55 pm »
I completely agree that they appear connected, however its possible that they are not. That said, since you know what the fuel pressure is supposed to be, I would fix this first and see what happens after that. So, on that regard, remove your regulator and plumb the fuel pump straight to the carb and see what the pressure is.

Yep, all you can do is go down the list, and eliminate one possibility at a time.
72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

2011 Kawasaki Z1000

Online 70chall440

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Re: Problem with 850 DP Holley
« Reply #111 on: July 11, 2019 - 04:45:42 pm »
 :2thumbs:
Current Mopar
70 Challenger RT 440-6 EFI, 73 Cuda 416-6 EFI
05 Hemi Durango, 01 Ram 4x4, 14 Ram 2500 4X4, 10 PCP Challenger 6 spd RT, 01 Viper GTS ACR, 52 B3B w/330 Desoto Hemi, 70 Hemi RR (under const)
Past Mopars
9 x Challengers. AAR Cuda, 4 RR, 2 GTX, 4 Chargers, etc... (too many to list)

Offline cudabob496

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Re: Problem with 850 DP Holley
« Reply #112 on: July 11, 2019 - 10:32:09 pm »
:2thumbs:

this reminds me of another nightmare I had with a loose ground on an MSD box, combined with
me at the same time putting the wrong base gasket (there's two that look very similar) on my 850 Holley!
« Last Edit: July 11, 2019 - 10:34:04 pm by cudabob496 »
72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

2011 Kawasaki Z1000

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Re: Problem with 850 DP Holley
« Reply #113 on: July 11, 2019 - 10:58:52 pm »
Got to love old cars...  :stirpot:
Current Mopar
70 Challenger RT 440-6 EFI, 73 Cuda 416-6 EFI
05 Hemi Durango, 01 Ram 4x4, 14 Ram 2500 4X4, 10 PCP Challenger 6 spd RT, 01 Viper GTS ACR, 52 B3B w/330 Desoto Hemi, 70 Hemi RR (under const)
Past Mopars
9 x Challengers. AAR Cuda, 4 RR, 2 GTX, 4 Chargers, etc... (too many to list)

Offline cudabob496

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Re: Problem with 850 DP Holley
« Reply #114 on: July 14, 2019 - 11:43:03 pm »
Well, hard to believe, but a friend gave me an old electric fuel pump, and I hooked it up by
the fuel cell, and 10 psi at the carb. So, I regulated it down to 6 psi. So, worn cam lobe for
the fuel pump has got to be the issue. Gee, this was easy, after 3 fuel pumps, 3 filters, a regulator,
tearing down the 850 Holley twice, a new fuel pressure gauge sending unit, blowing out the fuel system twice, removing the alternator and draining coolant 10 times, and replacing all rubber hose! Still gotta get the block off flange for the fuel pump location, before trying to start it up, and see if that lean spot goes away. Will keep you posted! And no more fear of this was all happening because I did something really stupid!!
« Last Edit: Today at 01:50:45 am by cudabob496 »
72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

2011 Kawasaki Z1000

Online 70chall440

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Re: Problem with 850 DP Holley
« Reply #115 on: Today at 12:07:37 am »
Glad you are making progress, its always something for sure. I took my 52 Dodge B3B pickup out today, the Desoto 330 Hemi ran very good, however the left front brake started dragging to the point I had smoke coming out of it... Now I have to figure out what is going on there...
Current Mopar
70 Challenger RT 440-6 EFI, 73 Cuda 416-6 EFI
05 Hemi Durango, 01 Ram 4x4, 14 Ram 2500 4X4, 10 PCP Challenger 6 spd RT, 01 Viper GTS ACR, 52 B3B w/330 Desoto Hemi, 70 Hemi RR (under const)
Past Mopars
9 x Challengers. AAR Cuda, 4 RR, 2 GTX, 4 Chargers, etc... (too many to list)

Offline cudabob496

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Re: Problem with 850 DP Holley
« Reply #116 on: Today at 03:29:40 pm »
Glad you are making progress, its always something for sure. I took my 52 Dodge B3B pickup out today, the Desoto 330 Hemi ran very good, however the left front brake started dragging to the point I had smoke coming out of it... Now I have to figure out what is going on there...

good thing no fire
72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

2011 Kawasaki Z1000

Online 70chall440

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Re: Problem with 850 DP Holley
« Reply #117 on: Today at 07:02:40 pm »
Very true, as I rolled onto the property I was thinking I might have exactly that. Not sure what is going on there, might be a bad rotor, pads or caliper.
Current Mopar
70 Challenger RT 440-6 EFI, 73 Cuda 416-6 EFI
05 Hemi Durango, 01 Ram 4x4, 14 Ram 2500 4X4, 10 PCP Challenger 6 spd RT, 01 Viper GTS ACR, 52 B3B w/330 Desoto Hemi, 70 Hemi RR (under const)
Past Mopars
9 x Challengers. AAR Cuda, 4 RR, 2 GTX, 4 Chargers, etc... (too many to list)