Hey Guys
This past weekend, to try and cure a too rich scenario, I installed a Mr. Gasket fuel pressure regulator on my completely stock and 1962 coupe - set it to 5 psi. I also upped the dwell from about 24 degrees to 28 - any higher than that and she was not very happy at idle. Drove it at low speed around the neighborhood afterwards and everything seemed REALLY good. Cleaner running, super smooth idle. Happy. Drove it on our main road this AM - warmed up, ambient temp around 65F. Got to 45mph and it started sagging - losing power when it was in 4th gear and surging. Acting like not getting enough fuel frankly. Any initial thoughts? I'm assuming the FPR is not set high enough bc max pressure spec for the car is 6.5 psi. But I dont' know why it accelerates fine up to speed and THEN loses power when it's at speed. Something about what I did to the dwell angle? Would welcome thoughts before I go re-experimenting.
Have you checked your timing? Initial and both mechanical and vacuum in the distributor.
Greg Surfas
Not yet. Planning to. But it didn't surge/lose power at speed before I did the FPR and the dwell setting though. So I'd like to rule that out first.
I personally would not trust a cheap FPR.
Greg Surfas
Completely stock '62 coupe means that you have the mechanical fuel pump or am I wrong?
If you have the stock fuel pump, a FPR is not needed.
Quote from: Roger Zimmermann on December 04, 2023, 11:15:38 AMCompletely stock '62 coupe means that you have the mechanical fuel pump or am I wrong?
If you have the stock fuel pump, a FPR is not needed.
It's stock mech pump. One issue with these OG pumps, from what I've read, is that they start over pressuring a bit as they age - and cause a rich running situation (and mine's idling too rich) that you can only rectify with a PITA stock pump rebuild or a FPR. I'm gonna hook up a pressure gauge to see what it's actually pushing out. And yeah, it's a fairly cheap - but well reviewed - Mr Gasket FPR.
Suggest you take the FPR out of the line and see if your issues disappear.
Greg Surfas
Has issues like that in my 60 CDV and problem was low fuel pump pressure and vacuum leaks. I think ideal pressure was 6ish for these. I measure the fuel pump pressure with a gauge without the FPR. If the pressure insufficient remove it, you don't need it. Tackle these issues one at a time and test in-between to be able to gauge the results of each modification.
Quote from: Michael Petti on December 04, 2023, 01:19:42 PMHas issues like that in my 60 CDV and problem was low fuel pump pressure and vacuum leaks. I think ideal pressure was 6ish for these. I measure the fuel pump pressure with a gauge without the FPR. If the pressure insufficient remove it, you don't need it. Tackle these issues one at a time and test in-between to be able to gauge the results of each modification.
Will do.
I took off the FPR and no change. Then put dwell just back just like it was before I added the FPR and no change. The issue is still this loss of power and seeking between 35 and 40MPH. It almost seems like it's a 3rd to 4th gear shift issue - which would suck. Will be investigating further when I get fuel pressure gauge tonight or tomorrow. Will also check for vacuum leaks.
Added wisdom welcome.
Do check timing chain slack if the original
has not been replaced. Bruce Roe
Changing the dwell angle changes the timing, (though not the reverse). If I remember correctly, the dwell should be set at 30 degrees. After that is set, adjust the timing to spec with the distributor vacuum unhooked and the vacuum hose plugged.
Quote from: 3210mar on December 04, 2023, 09:02:29 PMChanging the dwell angle changes the timing, (though not the reverse). If I remember correctly, the dwell should be set at 30 degrees. After that is set, adjust the timing to spec with the distributor vacuum unhooked and the vacuum hose plugged.
Per the service manual between 28 and 30 is to spec. I've definitely got a few things going on. Will post up an observation when I get a fuel pressure gauge reading tomorrow.
If it's not a timing/vac issue, my money is on the replacement fuel pump. I've replaced and rebuilt many of them for myself and club members over the years. It's usually one or both of the little valves under the top cap. You can just remove the four screws to check it out. The repop ones are almost never properly seated (takes three indents with a 1/8th inch punch around the edge of each one). If they're in the right spot when you remove the top, use a little hook/ dental type tool to see if they're loose as they often fall back into place and look ok with no pressure.
Take care,
Ken Karrer
CenTex Reg. Dir.
I would also suggest to put the dwell at 30. Then recheck timing. I you want to rule out the transmission, put it in low, and try to get to the same RPM where you get loss of power in higher gears and see if loses power at similar RPM. It is tricky, but it might give you an idea.
If you have a new repro mechanical fuel pump, that is likely your problem. This forum is load with threads about the problems. I went through 4 myself in 12 months of driving. One was bad right out of the box. My fix was to get an original A/C fuel pump and have it rebuilt by Arthur Gould. Problem of engine ran much better after that in high gear. My total problem was solved by rebuilding the carburetor, but that was a separate issue.
This all assumes the float level in the carb is not too low, seen these symptoms occur for just that reason.
Hmmm. Possible it is. I actually lowered them recently after a rebuild. Running the Daytona carb new cylindrical 'non needle' float valves. I'm gonna raise 'em up a bit - after checking off the other stuff. THX
Quote from: kkarrer on December 05, 2023, 08:39:44 PMIf it's not a timing/vac issue, my money is on the replacement fuel pump. I've replaced and rebuilt many of them for myself and club members over the years. It's usually one or both of the little valves under the top cap. You can just remove the four screws to check it out. The repop ones are almost never properly seated (takes three indents with a 1/8th inch punch around the edge of each one). If they're in the right spot when you remove the top, use a little hook/ dental type tool to see if they're loose as they often fall back into place and look ok with no pressure.
Take care,
Ken Karrer
CenTex Reg. Dir.
Wow - so I finally hooked up the fuel pressure gauge. 1 PSI at any throttle. So there's one of my issues for sure. Next step would seem to be a rebuild.
The other test to perform is a flow test.
As in measuring the amount of fuel that flows out the hose whilst the engine is running. This tests the actual amount of flow, as there is a big difference between fuel delivery and pressure.
Over a measured time and amount and see how that marries with the Shop Manual.
The easiest way to do it is to disconnect the inlet from the Carburettor, and with a length of hose attached to the inlet pipe, and the other end into a container, away from the engine bay, start the engine and time it for say 10 seconds (The Carby float chamber will still have fuel in it after turning off)
(By not letting the engine stall from an empty fuel bowl, enables you to reconnect the fuel line, and start the engine without having to crank the Starter Motor to refill the Bowl.)
Bruce. >:D
So I took off the fuel pump and took it apart. Though I hadn't noticed it when I took off the outside top cap the first time, one of the two valves was indeed not seated perfectly. All the rubber pieces inside the pump were in good shape. So, I took a socket extension and a socket that fit inside the valve seat and set the center piece on the ground and gently hammered the valve back into the seat with a rubber mallet. Did the same thing with the other side valve to be safe. Found out about the valve seat issue with this excellent little video (below) of a 1959 pump repair. When I got it in place, I then lightly peened the edge of the valve seats to put a tiny lip of aluminum on either side of the valves so they would stay in place in the future. Reinstalled it, and she fired right up and idled flawlessly with 6PSI of fuel pressure on the gauge- a far cry from the 1PSI I had a few days ago. That's right where it's supposed to be. Haven't had a chance to drive her to see if the apparent starvation is cured, but I'm optimistic.
I highly recommend this video btw. It could save you a lot of dollars and fuel pump hassles.
Very good video. Thanks for posting. Clay/Lexi
Anyone know if the pump in the video was an original 59 or a later replacement? I wasn't expecting it to be constructed like that in 59. That design with the valves seems more like it was designed for production cost savings than function and serviceability. Or was the change in that kind of thing ww2? Pre war stuff the valves would have all been threaded one way or another.
Quote from: TJ Hopland on December 17, 2023, 11:46:12 AMAnyone know if the pump in the video was an original 59 or a later replacement? I wasn't expecting it to be constructed like that in 59. That design with the valves seems more like it was designed for production cost savings than function and serviceability. Or was the change in that kind of thing ww2? Pre war stuff the valves would have all been threaded one way or another.
I think they were built like that for all the models that use that pump - and that equates to a bunch of years and thousands of pumps. I think the problem comes in rebuilds generally -- they don't fix the valves into the seats well and then you end up with the issue of 'em coming unstuck. The 1962 I had from 1986 to 2000 had the same fuel original pump for the entire time I owned it. So quality control was obviously real good on the original pumps.
In the 1980's I had that issue with a 1958 pump. I had to re peen the valve into its recess, I agree it was a rebuilder issue.
Just took her out for spin with the newly peened in valves.
Runs great at highway speed - so problem solved.
Now to set the timing a bit better and make a few fine point adjustments to the carb.
STOKED. Thanks for the help/advice.
I'm heading down the road and I ain't coming back.
Quote from: dixoncj on December 18, 2023, 02:26:27 PMJust took her out for spin with the newly peened in valves.
Runs great at highway speed - so problem solved.
Now to set the timing a bit better and make a few fine point adjustments to the carb.
STOKED. Thanks for the help/advice.
I'm heading down the road and I ain't coming back.
Great record, gotta love Warren Smith, Sun rockabilly at its best.
I have had so much trouble of this sort with
really old and high mileage cars, I have started
installing fuel pressure gauges (latest solid
state design) to keep track of things. Here is
a 15 psi setup for a carb, just move the decimal
when reading it. Bruce Roe