Best Fuel Pump Advice for Newb...

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MOPAROFFICIAL said:
Save your money for good headers, cam, heads, Etc and don't buy the fancy water pump, fuel pump, alternator and all that because the stock stuff works Beyond stock stuff
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MOPAROFFICIAL - I'm trying to show this Scamp love. When I received it, it would crank, but that's about the limit of it. The body was straight and clean. But it needed A LOT. One of the things was the exhaust was rotting out. So I replaced the ENTIRE EXHAUST. TTi headers, AFR bungs, AFR gauge (best thing ever), X-Pipe, 2.5" pipes, Borla mufflers, and pencil tips. That's just a small portion of what all has been done.

That said, I'm agreeing with your quote above. Which leads me to the question: Do you have a part number for the stock 340 replacement fuel pump?


7milesout
 
I bought mine from kragen auto parts, it's that old. But here's the napa version, with specs
They push enough, just not enough GPH for serious racing, but great for the street and limited strip action.

Screenshot_20180928-114137_Samsung Internet.jpg


Screenshot_20180928-114149_Samsung Internet.jpg


To put this in perspective

Screenshot_20180928-114751_Samsung Internet.jpg


Screenshot_20180928-114758_Samsung Internet.jpg
 
I agree. Stock should do it.
The flow specs in the listings above are probably not comparible to the specs they post for their 'performance' pumps.
Minumum stock flow spec was .25 gal/min which is 15 gal per hour.
This is measured at 500 rpm! The 25 gph claimed is probably also at 500 rpm, but good luck if you actual try to get a real answer.
Point is, the free flow for 'performance pumps' is always at high rpm, and is fairly meaningless without knowing the rpm.
Free flow at idle is useful because that's a real test for a mechanic.
 
Thanks guys. Your advice is valuable and appreciated. I will probably purchase the M6866 because I'm not too far from the Summit Racing in GA. I won't be able to get to it this weekend as I will be off at a BMX race all weekend.

As for my thinking, in post #25, I've pretty much replaced everything in the fuel delivery department, except the lines themselves. And they seem to flow like a geyser, and don't leak. My thinking to just replace the fuel pump with another $20 fuel pump is completely reasonable, IMO. I'm not out in left field am I? I mean, if it were a $600 pump, I'd want to check and test everything but the kitchen sink. But, for $20, and the fact that I don't know anything about the pump I just pulled off, except that it had a truck load of crap run through it before I replaced the tank, just makes sense to replace it.


7milesout
 
Not that I think this has anything to do with your problem, but your filter location isn't great. Generally, you find the factory fuel filter in a different place. I like to go for the frame rail close to the fuel pump side of the engine. Metal filter in a metal bracket secured to the frame rail with a couple of sheet metal screws. I also prefer to plumb the filter on the inlet side of the pump, rather than between the pump and carburetor. That way, the filter is away from heat sources such as the intake manifold, where vapor lock might become an issue with ethanol laced gasoline. It also cleans up the engine area a little.
 
7milesout said:
I won't be able to get to it this weekend as I will be off at a BMX race all weekend.
7milesout
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Well, I lied. I was in Augusta, GA until 1 pm or so on Sunday. I enjoyed a nice drive home. About 3/4th of the way to Atlanta from Augusta on I-20, I cut off and drove down through the country, to McDonough. It was nice to put the windows down and listen to the mighty Cummins rumble through small towns and the country. It has a 5" straight pipe (no muffler, no cat, no resonator). It was such a pleasant ride. My son and I went to Summit Racing. $21.XX and in 10 minutes later we were back in the truck. Very efficient at that place.

We went home, I took a short break. After that I was in the mood to mess with the Scamp. Only thing on my mind was to make forward progress and I would finish it on Monday. But it all went back together real slick. I got it all put back together and ready to fire.

But I didn't fire it up because it was dark out, my garage is not all that well lit so it would not be easy to spot fuel leaks. And my wife is not a big fan of untreated exhaust fumes … while I love 'em. And, even though the Scamp is not nearly as loud as some of your cars, it does send vibrations throughout the house (some pictures rattle on the walls and some window panes rattle). I love that … the wife meh, not so much.

So, I'll fire it up tonight and check for leaks. I drove it home last time on fumes so it wouldn't leak so much gas when I went to work on it. So, I will head to the gas station first thing if there are no leaks. After fueling, I'm going to do some 10 second pulls and see what happens.


7milesout
 
UPDATE!

Everything was good to go, no leaks. I had my son bump the starter several times, to turn the engine over and even during the 2 or 3 revolution bumps, I could tell the new pump was pushing more fuel into the filter. It's good to have a clear filter.

It filled the filter pretty good, so I went ahead and cranked it and drove it to the fuel station and filled it up. I checked the mpg after filling it up. Previously, I drove it to the track, ran it down the track 5 times and drove it home. 15.7 mpg. Not great. Not horrible. The best I've seen with it.

Anywho, after filling it yesterday, I did some 10+ second pulls. All the way to the 90 mph zone. It never went lean. It never fell on its face. So … that was it. Just needed a new $20 fuel pump.

The only strange thing is that now at WOT, I'm now seeing a steady 13.2 AFR. Before it was at 12.2 AFR, which is rich best torque. So, I'm going to go to my handy - dandy spreadsheet to determine the size needed for the secondary main to bring it back to 12.2. Can't see why a fuel pump would have any bearing on WOT AFR. Maybe it's got to do with the fuel, I don't know. But it needs more fuel at WOT for sure. 13.2 is safe, but optimal H.P. is achieved at 12.2 (at least that's what I've learned).

Thanks all you guys! A special thanks and a couple cold virtual brewskis going out to MOPAROFFICIAL and Mattax!


7milesout
 
I wished! :D Stir that pot Mr. Fife! :D

I'm only hitting 97 mph after about 14 - 15 seconds (depending on how much I spin on the line).
 
7milesout said:
I wished! :D Stir that pot Mr. Fife! :D

I'm only hitting 97 mph after about 14 - 15 seconds (depending on how much I spin on the line).
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Not to dump another opinion on you, but you mentioned taking time to get fuel to the carb.
This video is after installing a Carter electric rotary vane pump back at the tank.
Dead headed (no return) fuel systems are hard on pumps due to heat buildup from the pump working against fuel that isn't moving when say sitting at stoplights idling.
In a return system the pump has cooler fuel running through it all the time, so this minimizes the heat buildup in the pump.

I ran new 3/8 nylon 12 (EFI line) up to the carb and T off right at the carb for the return line and back to the tank.
Used a gauge on the feed line to watch the pressure as I tried different restrictor orifice's in the return line.
Once I had the right size restriction in the return line I had 6psi at the carb inlet with the pump running.
No regulator to mess with or mount and plumb.
I drilled my factory style sending unit and added a return fitting, and the OE vent line was untouched.

Circulating cooler fuel eliminates vapor lock and fuel boiling in the lines in hot weather, plus you end up with cold starts after sitting like this.

www.classichei.com/dart/morningfire.avi
 
MOPAROFFICIAL said:
I bought mine from kragen auto parts, it's that old. But here's the napa version, with specs
They push enough, just not enough GPH for serious racing, but great for the street and limited strip action.

View attachment 1715228990

View attachment 1715228991

To put this in perspective

View attachment 1715228992

View attachment 1715228993
Click to expand...
I have the carder muscle car series on two vehicles and they work fine.
One is on a 340 and another on a 360 neither engine is stock, and they have never starved for fuel.
 
P4007040; 80gph@8.7psi.....She's been serving well since 2004 .
I think that works out to 290liters per hour.And 80gph is 480 pounds of gasoline, per hour. Can you run a tank on that?
IDK, but at .5 pound per horsepower per hour, a 440hp engine only needs 220pounds/ hour,3.67 pounds per minute,.061 pound per second or .733 pound for a 12 second quarter mile, which works out to 15.6ounces, or a half a qt..
Per mile that would be 62oz/1.9 quarts/.484gallon......... per mile. Ergo 2.06mpg.
But the pump is spec'd for double that and change.

So any old pump that puts out 15.6oz in 12 seconds, is theoretically capable to feed 440 horsepower down the the quarter, allbeit with no reserve. Hang on the 4150 stores about 50cc in each bowl, or 1.7oz. If 80% of that is useable at speed, that's 2.7 ounces less, that the pump actually HAS to put out... so say 13 oz.
BTW; 15.6 oz/1.7 = 10.77 bowlfuls in the 12 second quarter........ and you start preloaded with 2 bowlfuls.
I think the math is good,lol.
 
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AJ/FormS said:
P4007040; 80gph@8.7psi.....She's been serving well since 2004 .
I think that works out to 290liters per hour.And 80gph is 480 pounds of gasoline, per hour. Can you run a tank on that?
IDK, but at .5 pound per horsepower per hour, a 440hp engine only needs 220pounds/ hour,3.67 pounds per minute,.061 pound per second or .733 pound for a 12 second quarter mile, which works out to 94ounces.
Per mile that would be 2.9quarts, or .73gallon......... per mile. Ergo 1.36mpg.
But the pump is spec'd for double that and change.
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The p4007040 was a Carter M6270. Glad its worked for you. I used one for a long time. It can be troublesome when engine braking because of the high cutoff pressure. The 80 gph is the advertised free flow. In other words, pumping into a bucket. The 7 - 8 psi is the advertised cutoff pressure. In other words no flow allowed out, carb inlet valve shut.

I sent my M6270 to Ryan Brown in Canada along with some other pumps to be tested. Cutoff was 7.5 psi. Maximum flow at 4.5 psi was 70 gph @ 6000 rpm.
Graph of the flow vs rpm@ 4.5 psi about mid-page here: Mechanical Fuel Delivery for Mopar LA Engines
 
7milesout said:
The only strange thing is that now at WOT, I'm now seeing a steady 13.2 AFR. Before it was at 12.2 AFR, which is rich best torque. So, I'm going to go to my handy - dandy spreadsheet to determine the size needed for the secondary main to bring it back to 12.2. Can't see why a fuel pump would have any bearing on WOT AFR. Maybe it's got to do with the fuel, I don't know. But it needs more fuel at WOT for sure. 13.2 is safe, but optimal H.P. is achieved at 12.2 (at least that's what I've learned).
Click to expand...
It's possible the pumps have enough difference in the return spring the fuel level is now a little lower. Even so, that usually a fine trimming - nothing near a full AFR ratio - and would impact low throttle the same or maybe even more. Maybe something to do with whatever was wrong with the old pump. All speculation anyway.

As far as adjusting the main jets; if it needs richer, it needs richer on all four corners
if it was dialled in, with the prim/secondary jetting as you had it. If it was dialed in, I'd just go one size larger on all four and see if mph increases.
If it wasn't dialled in that close, then SOP would be 2 jets sizes up on either the primary or secondary and see if mph increases.
Then check the spark plugs to be sure WBO2 meter isn't misinterpreting what's going on.
 
AJ/FormS said:
P4007040; 80gph@8.7psi.....She's been serving well since 2004 .
I think that works out to 290liters per hour.And 80gph is 480 pounds of gasoline, per hour. Can you run a tank on that?
IDK, but at .5 pound per horsepower per hour, a 440hp engine only needs 220pounds/ hour,3.67 pounds per minute,.061 pound per second or .733 pound for a 12 second quarter mile, which works out to 15.6ounces, or a half a qt..
Per mile that would be 62oz/1.9 quarts/.484gallon......... per mile. Ergo 2.06mpg.
But the pump is spec'd for double that and change.

So any old pump that puts out 15.6oz in 12 seconds, is theoretically capable to feed 440 horsepower down the the quarter, allbeit with no reserve. Hang on the 4150 stores about 50cc in each bowl, or 1.7oz. If 80% of that is useable at speed, that's 2.7 ounces less, that the pump actually HAS to put out... so say 13 oz.
BTW; 15.6 oz/1.7 = 10.77 bowlfuls in the 12 second quarter........ and you start preloaded with 2 bowlfuls.
I think the math is good,lol.
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Where are your floats set in that scenario?
 
MOPAROFFICIAL said:
I'm feeding 410cid. Full ported heads ,solid roller, 750 carb, tti step headers, 4 spd, 3" pipes 3.73 gears....I rev it 6800


I use a stock 340 replacement fuel pump.

Think about how long you hold it at wide open throttle. Save your money for good headers, cam, heads, Etc and don't buy the fancy water pump, fuel pump, alternator and all that because the stock stuff works Beyond stock stuff
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I wouldn't expect a stock pump to be sufficient for your application. Maybe hammering around on the street, but I bet running WOT for a 1/4 mile would be pushing the stock pump to the limit.
 
forphorty said:
I wouldn't expect a stock pump to be sufficient for your application. Maybe hammering around on the street, but I bet running WOT for a 1/4 mile would be pushing the stock pump to the limit.
Click to expand...


Idk, I've wot to 140 or so mph. I havent encountered any starvation that showed itself to be noticable. The other day I had a turbo 565 hp Audi pull up at the next light and tell me "that thing is sick" after BARELY closing in on me but not quite while following me in the next lane "we both blew around a couple cars to get some open range to get on it" from a stop light before. I'm only using a 780 demon, 5/16 line ..and I really didnt even get though 3rd before i hit some road fodder "other drivers in the way". I have to mention it's nice
some people still have some class at the next light and not pull off or run the red like a biotch. In fact twice that day with a Camaro afterward n the dude saying 'that thing is loud when you got on it'. Yep...that's what you hear as I leave you in the rear view mirror, queer. Jk lol had too anyhow...I'm thinking more like nascar, 700hp for 500 laps, or nitrous, forced, turbo, 12.5 comp vs extended 7500-8500rpm etc...then the stock pump ain't cutting it... but your average sb or bb ,stroked or not , stock works despite what you read on the net....
 
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7milesout said:
Well, I lied. I was in Augusta, GA until 1 pm or so on Sunday. I enjoyed a nice drive home. About 3/4th of the way to Atlanta from Augusta on I-20, I cut off and drove down through the country, to McDonough. It was nice to put the windows down and listen to the mighty Cummins rumble through small towns and the country. It has a 5" straight pipe (no muffler, no cat, no resonator). It was such a pleasant ride. My son and I went to Summit Racing. $21.XX and in 10 minutes later we were back in the truck. Very efficient at that place.

We went home, I took a short break. After that I was in the mood to mess with the Scamp. Only thing on my mind was to make forward progress and I would finish it on Monday. But it all went back together real slick. I got it all put back together and ready to fire.

But I didn't fire it up because it was dark out, my garage is not all that well lit so it would not be easy to spot fuel leaks. And my wife is not a big fan of untreated exhaust fumes … while I love 'em. And, even though the Scamp is not nearly as loud as some of your cars, it does send vibrations throughout the house (some pictures rattle on the walls and some window panes rattle). I love that … the wife meh, not so much.

So, I'll fire it up tonight and check for leaks. I drove it home last time on fumes so it wouldn't leak so much gas when I went to work on it. So, I will head to the gas station first thing if there are no leaks. After fueling, I'm going to do some 10 second pulls and see what happens.


7milesout
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Too bad you didn't let me know. We could have met for lunch.....on me. I am only about 60 miles south of Summit.
 
Mattax said:
It's possible the pumps have enough difference in the return spring the fuel level is now a little lower. Even so, that usually a fine trimming - nothing near a full AFR ratio - and would impact low throttle the same or maybe even more. Maybe something to do with whatever was wrong with the old pump. All speculation anyway.
Click to expand...
Now that you mention it, it did seem a skosh leaner just cruising around, but not nearly 1 full point. But an interesting bit of info there.

Mattax said:
As far as adjusting the main jets; if it needs richer, it needs richer on all four corners
if it was dialled in, with the prim/secondary jetting as you had it. If it was dialed in, I'd just go one size larger on all four and see if mph increases.
If it wasn't dialled in that close, then SOP would be 2 jets sizes up on either the primary or secondary and see if mph increases.
Then check the spark plugs to be sure WBO2 meter isn't misinterpreting what's going on.
Click to expand...

Mattax - This AFR gauge is an incredible tool. Maybe you've used one. I made a spreadsheet that calculated jet sizes, metering rod sizes and what changes from one to another will do. And when I make a change to the actual parts, the AFR gauge reflects almost exactly what my spreadsheet says. Not that my spreadsheet is EXACT. There are factors in the real world that come in to play. But the spreadsheet is a great tool for RELEVANCY. What I mean is, if I want to go 1 full point richer at WOT, my spreadsheets are accurate enough to nearly always put me on the correct jet change right off the bat. No guessing. The AFR gauge confirms it. And it confirms there are enough real world factors that I need just a bit more or less to make it perfect. I swear, the buttometer agrees that 12.2 is the sweet point. I will get this to 12.2 at least by this weekend. Getting smoked at work and personal crap (working on my sister's car). For real, I don't need to check the spark plugs any more. The AFR gauge is so consistent, I can tell when its wrong or lying. It's only been wrong once before, and I could tell it was lying when driving the car. It had a problem and Summit replaced it for free.
 
RustyRatRod said:
Too bad you didn't let me know. We could have met for lunch.....on me. I am only about 60 miles south of Summit.
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I'll let you know next time I go to Summit. It won't be long. As I will be buying an Air Gap intake before too long, since it seems I have this starvation issue on the run. But 60 miles is an awfully long ways to go to buy me lunch. I'm about 20 miles from Summit. Unless it's raining, I'll drive the ole Scamp to Summit.
 
Guys - To keep this short, I changed it from 0.092's to 0.095's. The AFR's would run about 12.7.

I then changed it from the 0.095's to what's in it now which is 0.098's. The AFR's are now hitting about 11.7.

I want to run it down the strip tonight. My target AFR is 12.2. Am I better off with 11.7 or should I go back to the 12.7? It's going to get a bit chilly tonight. I'm thinking I may be better off with 12.7, and colder temps may pull that down a bit more.

Input appreciated.
 
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