I’m probably skimming over this this watch to quickly but reading about your low fuel pressure and how it drops, I’m wondering if you have a non-vented fuel cap on the tank and the pump is sucking down a vacuum in the tank?
I think I got taken to the bank
- Thread starter JARRETT LYNCH
- Start date
At this point, with an extra fuel pump in hand, I would lay a weld bead on the arm to add height to it and see if it improves delivery. It has to be the rod, pump or cam lobe.
Going electric is fine but any of the Holley pumps are loud and you will also need a regulator.
Going electric is fine but any of the Holley pumps are loud and you will also need a regulator.
#41
Well-Known Member
There are some simple in-line electric 12v pumps that you can insert into rubber fuel line that will give you enough pressure to check run condition. That will narrow it down. I keep a couple for that purpose and transferring fuel from tanks and containers. No more mouths full of gasoline.
Curiousyellow71
Well-Known Member
I do not know what fuel pressure gauge you have...but if its fluid filled there is a plug you have to pull on the gauge or it will give a bad reading. It will keep reading lower the longer you run it! Fluid filled gauges stink as fuel pressure gauges.
- Local time
- 12:00 AM
- Joined
- Sep 15, 2009
- Messages
- 22,171
- Reaction score
- 46,383
- Location
- State of insanity
On a related note, shouldn't it be "taken to the cleaners" ???
I had a wiped lobe on my cam which led to the same problem as yours. I put a pencil in the pushrod hole and cranked the motor. The pencil hardly moved. Rather than changing cams I did the electric fuel pump. Kinda nice filling the carb before cranking.
JARRETT LYNCH
Member
Ok, after some feedback from you guys I removed the distributor and looked down and while my wife cranked the engine over I could see the pump rod moving in and out a good amount. I would guestimate around .4-.5". That seems fine to me. Now I'm really scratching my head. Could I have a brand new fuel pump that is bad?
JARRETT LYNCH
Member
Both of the gauges I used are fluid filled and the only plug I see on them is the plug that allows you to add the fluid. Why would there be a plug that you have to remove?
Tank venting has been mentioned. You said that there was no sock on the fuel sender/pickup, but blew air through it, it could still have something in it. Something here isn't making any sense.
Have to admit, I've made the same mistake and not read the destructions before. Then I did.
JARRETT LYNCH
Member
I pulled the pickup out all the way out and inspected everything. All the lines are brand new from front to back. I do notice when I start it cold the pressure is higher and then slowly drops as engine warms up. Kind of like what Currious Yellow was mentioning about the fluid filled gauges and having to remove a plug.
Curiousyellow71
Well-Known Member
The engine heat warms the fluid giving it a false reading.
Better then explaining it, here is a link below. On our car the pressure gauge goes to zero after it warms up wo messing w the vent.
https://static.summitracing.com/global/images/chartsguides/s/sum-800199.pdf
Last edited:
autoxcuda
Well-Known Member
What does the fuel line metal and rubber look like from the fuel pump to the carb?
Where were you measuring fuel pump pressure between the pump and the carb?
Pictures of the fuel lines from pump to carb to get a second set of eyes on it?
Where were you measuring fuel pump pressure between the pump and the carb?
Pictures of the fuel lines from pump to carb to get a second set of eyes on it?
autoxcuda
Well-Known Member
Found this from your previous thread:
Last edited:
JARRETT LYNCH
Member
That’s weird, I’ve used countless fluid filled gauges and have never had a problem with readings and have never touched any vent
JARRETT LYNCH
Member
Everything from tank to carb is brand new and has been double checked for any plugs/debris. Fuel pick up and steel line has been upgraded to 3/8 stainless. Brand new Edelbrock fuel pump and I have brand new 3/8 rubber fuel line from pump to filter to Edelbrock fuel feed fuel rail for VRS carb. All vents on tank are new and I have tried removing fuel cap. Cam lobe appears to be ok visually as it’s moving rod in and out about .4-.5” near as I can tell. I don’t know what the spec should be.
70 sublime
Well-Known Member
- Local time
- 12:00 AM
- Joined
- Mar 19, 2020
- Messages
- 451
- Reaction score
- 844
- Location
- Port Hope , Ontario
You can not tell how long the fuel pump rod is just by looking down the distributor hole and see it move
If you see it move how ever far you thought all that proves is the lobe on the cam is doing its job
If the rod is short it will not reach far enough to give the pump a full push everytime it pumps
You have spent money and changed everything else there is so what is another $50 for a new push rod ?
JARRETT LYNCH
Member
I guess you didn’t read any of my posts. I pulled the pump rod and inspected and measured it- it’s 3.21”
Similar threads
