1960s 62 - Losing power above 45 - Fuel delivery or points?

[dixoncj]

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.

["Cadillac Kid" Greg Surfas 15364]

Have you checked your timing? Initial and both mechanical and vacuum in the distributor.
Greg Surfas

[dixoncj]

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.

["Cadillac Kid" Greg Surfas 15364]

I personally would not trust a cheap FPR.
Greg Surfas

[Roger Zimmermann]

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.

[dixoncj]

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.

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.

["Cadillac Kid" Greg Surfas 15364]

Suggest you take the FPR out of the line and see if your issues disappear.
Greg Surfas

[Michael Petti]

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.

[dixoncj]

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.

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.

[bcroe]

Do check timing chain slack if the original
has not been replaced.  Bruce Roe

[3210mar]

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.

[dixoncj]

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.

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. 

[kkarrer]

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.

[Julien Abrahams]

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.

[Michael Petti]

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.

[Dave Shepherd]

This all assumes the float level in the carb is not too low, seen these symptoms occur for just that reason.

[dixoncj]

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

[dixoncj]

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.

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 Tassie Devil(le)]

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.

[dixoncj]

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.