4.3 replacement motor. Having some fuel problems

[jbwrangler]

I recently purchased a 2008 regal 1900 with a cracked block. I bought a brand new GM 4.3 Marine long block and swapped over all the accessories from the old motor. I added an Edelbrock 2519 intake and 1409 carb tuned to Rick Stephens and Volpins specs. ( .095 primary jets, .092 secondary jets, .065" x .057" meter rods, 7" pink step up springs, and .043 acc pump nozzle)

I got everything connected up one evening and the new motor started right up. I went to bed happy. The next day, she started up and idle for a minute or so and then died and would not restart. To try to determine if the problem was fuel or spark, I squirted a little gas down the carb and she tried to crank. I then took the top off the carb and no fuel in the bowls. Both needles were stuck in the up (closed) position. I readjusted the floats and reintalled. Started up and ran great. Shut off and then same issue as before. Disassembled carb and floats stuck up again. After cranking with the key in th eon position I can hear the fuel pump pumping until t he oil pressure falls below 8lb.

Any ideas? Could my fuel pressure be too low, even though it is pumping fuel? Fuel pump shot? I removed the fuel line and pumped a gallon or more into a clean bucket. Fuel looks good.

My next step is to get a fuel pressure tester I guess?

Thanks in advance

 

[alldodge]

The carb shouldn't be getting stuck closed. Hey Rick Stephens have any ideas

 

[Lou C]

is it a new carb? how do the needles and seats look? Any sign of the float rubbing on the side of the float bowl? If its not a new carb I'd consider changing the needles and seats and make sure the float moves freely.

 

[Rick Stephens]

Sorry I'm late to the party. A forest fire east side of Seattle burned up a couple miles of fiber and the only internet left here in northern Idaho is cell phones. Interesting times, feel for those more effected than I.

I've never seen stuck needle on a new carburetor. Either pressure is too low or there was an error in the manufacture of said needle and seat, or they don't match. You can get a replacement at any auto parts store. The hardest part of checking pressure is figuring out a fitting to attach a pressure gauge to the line. You don't need to T the line, just attach to the carburetor end and connect power to the outside 'prime' lug on the starter to run the pump for the test.

Best of luck. Bet it's something simple.

Rick

 

[jbwrangler]

Carb is brand new. I talked to Edelbrock yesterday and they had no ideas. I removed the fuel line and anti-siphon valve yesterday. Valve looks ok, but I may replace anyway. Fuel line def needs replaced. Looks like a plastic liner came off the line and is curled up inside. Never seen this before. Fuel line is only 15" long. Will update after replacing those two items.

 

[Lou C]

wonder if bits of that got past the filter and is jamming the needle valves...I'd take the top off the carb, disconnect the fuel line and remove the floats & needles, if you can remove the seat then blow compressed air through the fuel inlet to clean out the passage leading to the seat.

 

[nola mike]

Are the needles stuck, or the floats? My 1409 when I checked actually seemed like the needles were stuck as well. Dropped the floats and they stayed put. I used some compressed air from my mouth into the fuel inlet and they dropped though--easily something that a fuel pump would overcome.

 

[jbwrangler]

Well new fuel line and anti-siphon did not fix the problem. The carb is clean.

Nola, the needles are stuck up (closed). Just as you describe. floats hang down, but the needles stay up.

Only thing I can figure at this point is the fuel pump isnt putting out enough pressure. Seem weird though because it pumps fuel great.

 

[Mlevy]

Are the fuel bowl baffle plates in backwards? I think the floats will stay shut if the are.

Mitch

 

[jbwrangler]

Are the fuel bowl baffle plates in backwards? I think the floats will stay shut if the are.

Mitch

I have not removed them, so I don't think so. When I free the needles and reinstall it works fine for a little while (until the bowl enpties.

 

[jbwrangler]

OK, so I pressure tested the fuel pump. 7lbs of pressure. Edelbrock recommends 5.5-6.5, but too much pressure should give me the flooding, not fuel starvation.

 

[Rick Stephens]

OK, so I pressure tested the fuel pump. 7lbs of pressure. Edelbrock recommends 5.5-6.5, but too much pressure should give me the flooding, not fuel starvation.

Wow. Ain't that a regular reaming. I would probably go get a cheapy rebuild kit and see if swapping the seats and needles works. I'm impatient though. Edelbrock should be wanting to fix this. Kinda hard to calibrate when it don't run longer than a few minutes.

 

[jbwrangler]

Wow. Ain't that a regular reaming. I would probably go get a cheapy rebuild kit and see if swapping the seats and needles works. I'm impatient though. Edelbrock should be wanting to fix this. Kinda hard to calibrate when it don't run longer than a few minutes.

Yes! Getting pretty frustrating! Rick, just to be sure I tested the pump correctly....I unhooked the fuel line where it goes into the carb and connected a fuel pressure gauge/vacuum gauge. Then cranked it over until the FP kicked on. , then left the key on for a few seconds ( the FP still runs until the oil pressure gets below 8lb or so). Is tht an ok way to test?

 

[Mlevy]

Could do the same type of test with the fuel into a 5gal bucket you did previously but with the top of the carb attached to the line. Then you can see what’s going on.

 

[jbwrangler]

Could do the same type of test with the fuel into a 5gal bucket you did previously but with the top of the carb attached to the line. Then you can see what’s going on.

Great idea. May try that tomorrow.

 

[Rick Stephens]

Your test was fine. All we care about is what the pump puts out when spinning, you got that. Time to hammer on Edelbrock.

 

[Mlevy]

I agree Rick but it would be a good way to see what is happening, wether it’s just the needles and seats getting stuck or something else. Also it costs nothing which is even better!

 

[Lou C]

sometimes even new carbs come not right, I had this with the Holley 4160 I tried a couple of years ago, I had no end of trouble with it (very rich running, rough running etc) went back and forth trying different things from speaking to Holley techs, finally pulled out my old Quadrajet rebuilt that and its been fine. Had to satisfy my curiosity though and took the Holley nearly totally apart, and found that, the clutch bolts holding on the secondary metering plate were loose, allowing extra fuel flow from the secondary bowl....which caused the extreme rich condition....
In this case its possible the seats or the needles were not machined right...

 

[jbwrangler]

I ordered a set of replacement needle just to try. They are hi- flow because that is all I could get quickly. Not sure what the turn around would be on a replacement 1409. No one seems to have them in stock.

 

[nola mike]

Did you try Mitchlevy 's test? Curious as to how stuck those needless (both of them?) actually are. Like I said, mine didn't drop on their own, appeared stuck but would definitely drop with fuel pressure applied