I have been having a fuel issue, finally hooked up a pressure gauge just before the carb, after the filter. It's a 350 with an Edelbrock 600 on top. The pressure gauge reads 4.5 psi both at idle and when I rev it up. The pump was a Carter and is about 10 years old, and has been sitting in a box for about the last 5 of those years. The question:...Is the pump not pushing enough fuel, or is the carburetor not taking enough? From what others have suggested, it should be pushing 7 or so, and have a regulator bringing it down to about 5. Thanks.
I have no clue which Carter it is...I should add that I only THINK it's a Carter...it was 10 years ago that I bought it. It used to keep this same engine fed just fine with a Holley 750 (3310) and a 600 (1850). I'm more or less just wondering about the priciple of fuel pressure...does this mean that the pump is not putting out enough, or does will the carb take what it needs?
For Edelbrock carbs, 5psi is enough. You are close enough to not have problems. What is the issue? What problems are ya having that makes you think of the pressure?
Here is a video of what it's doing. The consensus is that it's not getting enough fuel. It got better when I moved the accelerator pump rod to the top hole, so that seems to be a step in the right direction. http://www.youtube.com/watch?v=DRFl7kBxK9E You'll hear it click once loudly, then three times a little quieter. It loses all steam when this happens.
Have you checked the little br*** screens in the carb near the needle and seats? I had an issue similar to yours a while back and my problem was **** in the screens. It would flow enough fuel to allow for low speed driving but not wide open throttle. A little while later, it wouldn't even do the low speed stuff. I cleaned the screens and all is well.
Are those screens under the airhorn, or is it the screen near where you attach the hose? I don't recall seeing any when I had the airhorn off. I was just on summit's site and even the stock AC/Delco pumps they have are rated between 5-6.5 PSI Max...this old "performance pump" is only pushing 4.5... That's the direction I'm leaning, however I did get a few good rips out of it before this problem happened, so whatever the problem is, it happened while I was driving it. I got two or three good rips out of it, now what happens in that video happens every time.
I am having the same problem with my Carter pump. My Holley pump shot ****s on me so I picked this one up. I run a fuel pressure gauge and its reading 4psi. Looks like I will be going back to a Holley. I was running 2 x 4 tunnelram setup with 1/2" fuel line. I pulled that all off except for the fuel line and now run a 750 DP Holley. It would seem to me that the larger the fuel line the less pressure you will have. Don't know if that is true or not, just trying to use common sense. I was thinking 6 psi for the DP Holley. Thanks Keith
How do I go about testing this pig? To see if the issue is between the tank and the pump, I can disconnect the feed TO the pump and put a hose into a gas can and check the pressure then...that makes sense. How do I see if the issue is in the carburetor? Can I use a funnel to gravity-feed the carb, or will the pressure due to the gravity overcome the needles/seats and flood it? Will this 1405 run in a gravity feed setup and will reading the gauge at that point even tell me anything because I already know it will idle just fine at 4.5psi.
I had to do something like that. Had to put a lawnmower gas tank on top of the carb! Not good for full throttle. It will get ya to work, when it's only a few miles. Won't tell ya much. Pressure is only half of it. Gotta have the volume too. Sill got the Holleys? Put one back on for a test.
I think your fuel pressure sounds fine. I run 5 PSI for both my 600's. Did the car sit for the Winter with untreated gas in it? Had similar problems with the Edelbrock's on my Avatar which didn't get treated this year. Took the air horns off, cleaned out the float bowls, pulled the metering rods and idle mixture screws and blew air though them. Much improved after re***embly. Also running carb cleaner through each gas tank fill up. I'm told Edelbrock's are notorious for drying up (varnishing up). Lesson learned for me; treat with Stabil before Winter shutdown.
Johnnie, no other carb at all to test with, nor another fuel pump. rramjet, The tank actually ran dry when I went to take it for its first spin, so the gas is all new. Everyone keeps saying that they run 5 on theirs...I know 4.5 is close but half of one PSI might make a difference when you're only talking about 5...that is 10 percent less fuel pressure. I always say that "10 percent is ****" -but that only applies to retail discounts! It might MEAN something for A/F mixtures and what-not... I should just shut up and buy a new pump, this one's 10 years old anyway, how much longer 'til it ****s out on me, anyway?
If you got dirt in the fuel inlet the carb can run out of gas while the pressure gauge still shows pressure on the fuel line. The gauge proves that the pump is working up to that point. Are you sure you are running out of gas. You only need enough pressure to keep the carb full. It's not fuel injection where the pressure is critical. Sometimes we get locked onto a suspected problem and forget about anything else that can cause the same symptoms. I've done it myself.
tommy, all I know about it is what it's doing in that Youtube that I posted, that it was not spark plug wire related, and that moving the accelerator pump rod and/or resetting the float levels made it only happen above 2500 rpms, as the video shows. Before that, it was all over the place.
I am betting that it has **** inside the carb. Ya really need to do a volume test on the pump first (just to be sure). Running the tank empty, fresh fuel may have stirred up **** on the bottom of the tank. Volume test the pump and it will tell ya if it's the pump or the carb.
It could be dirt in the main jets not letting the fuel through. Changing the fuel pump won't help that. I don't think it's a fuel pump problem. Thanks I had to crawl behind the desk to hook up my speakers again to hear your Youtube. Now I have my ears on a gain.
The pump should produce a pint 16oz in about 15 seconds. disconect iginion and fuel hose from carb ,put hose in a container and crank for 15 seconds and measure how much fuel was pumped. A pint or better forget the fuelpump, go look for resrictions in the carb at the inlet working to the mainjet system. If that all checks out remember the old saying 90 % of fuel probs are iginion related and vis-versa.
Have you ever checked the inlet screen in your tank? My Olds used to fall on its face before 4000 rpm, the screen in the tank was fine mesh and clogged up with varnish. It was "only" 30 years old, just a youngster by HAMB standard
I just did John's test...15 seconds gave me just a "CH" over 14 oz. I was expecting it to either be 4 oz or close to 16 so it would be a true "GO or NO GO" result...but that 14 is 12.5% less than what we intended...so I still don't know for sure if this pump is junk. These screens in the carb...where are they? When I remove the floats and tip the airhorn upright, would they fall out WITH the inlet needles, or does something else need to be removed to get at them.... I was just thinking...maybe the problem IS my tank. How do I know for sure? Over a year ago, the engine just died on a steep hill (fuel gauge is broken) so I ***umed it ran out of gas. I rolled to the bottom of the hill and (because the fuel gauge is broken I had 4 gallons of fuel in a gas can in the bed) put the spare gas into the tank. It still didn't work. I thought the pump was broken but to diagnose that, I pulled off the pump inlet hose and nothing came out...even though I knew there was at least 4 gallons in the tank. I pulled the cap off and grabbed a spare hose I had, mated it to the hose that wasn't dumping fuel on the ground, and blew into it...it freed something up and fuel began to run...I just ***umed there was some kind of air pressure or vacuum differential that needed to be overcome...never had another issue, but I put a 3/8" filter coming out of the tank after that. Yesterday morning I changed that filter and when I reconnected the new filter and removed my kink/clamp, it didn't immediately fill up the see through filter I put in... Maybe Grumbler is right...How do I find out...The way I see it, I can go buy a new carb, new pump, new tank, and a new distributor and I'd be all set...but I don't really have $1,000 to find out that way. Thanks to everyone for the suggestions thus far.
Are you sure your ignition is running right? Wrong advance, too much advance can cause similar symptoms. check your dwell if points, then timing make sure advance is working.. i had a dizz that had too much centrifical and it would pop...
I just put on an Edelbrock and they recommended not more than 6.5 lbs. No minimum in their literature.
Run a temporary line from the pump to a gas can. Takes the tank and the line to it out of the equation. Sounds to me that you are getting enough gas to get way past 2500rpm though.
It's only happening when it's driving...maybe if I rev and hold it at idle it would do this... As for knowing if the ignition is good... The only things I know are good are the plug wires and plugs. I really cheaped out on the dizzy that's in there and I'm worried that is the problem- wishing I had just pulled the trigger and gotten a good one. It's one of those HEIs from ebay that seem too good to be true- 60,000 volts and lifetime replacement in exchange for some magic beans. I'd swap it out if a new one would just drop in...I think whoever built this engine left out some sleeve that's supposed to keep the oil pump drive from flopping around so it's a real pain in the *** to put one in this. I know that it ran fine for about 8 miles of me driving it like I just got my license, and felt good and pulled strong. Then I got on it one more time and got that violent CLICK you hear in the video, and it hasn't been the same since. Maybe the pump pulled some junk over that screen (I'm checking about a screen on a board that deals with those trucks), maybe something in that Chinese distributor popped. At first I thought it was a backfire, so I started making minor timing adjustments and driving to see if it was better, but it's done this since. The vacuum advance is not hooked up, and was never hooked up the last time this engine was run, when it had a Holley. I thought it was a plug wire that got too hot (OEM style were WAY too long so they were wrapped around each other and hanging here and there) so I changed those out with some nice MSD wires. That didn't help. Then I started messing with the floats and acc pump and one or the other of those adjustments made it more consistently happen later in the RPM band, now it's up past 2500- and that's if I believe my (****ty) SW tach, which jumps all over the place...as soon as my new tach gets here this one is going back. So...long story short, I guess if I ever do a swap again I need to buy two of every damn part that will go on it so I can swap parts in and out to see what's good and what isn't, work fast, and send the extra **** back.
Process of elimination. To take the tank and/or inlet screen out of the equation you could plumb in a temporary tank like a 5 gallon outboard type and then go for a drive. That will determine whether there is a fuel supply problem BEFORE the pump inlet at least and you could go from there. IF its a fuel problem. I've gone round in circles too with fuel/electrical gong shows. Its frustrating sometimes, hang in there, don't let it beat you
Chinese distributor= could very well be a problem. Verify that it is advancing properly and has the correct amount of advance. ALWAYS verify the ignition before messing with the carb. Easy to cover up ignition problems with the carb.
Grumbler, that's a great idea. I think the simplest thing I can do now is ratchet (or otherwise secure) my 5 gallon jug to the spare tire carrier and run a hose to it and see if that works any better...then I'll be able to rule out the tank. If it isn't the tank, I'll keep plugging away. Maybe I can call Carter and see if they have a recommended testing procedure, or if they can bless or condemn my 14 oz. result.
Well, It isn't the fuel tank. I rigged up my 5 gallon tank in the bed, ratcheted it to the spare tire (on the carrier), ran a hose to the fuel line and it still happens. Could it be the fact that I'm running a filter right out of the tank? It ran really good at first, too. I thought I figured it out. I got to the highway to do highway speeds and it started immediately as I pulled away from the stop sign, even though it never happened the previous 6 times I started from a stand still.
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