Problems with dual line conversion

[BlackoutBill21]

Sorry to beat a dead horse but I’m having the same problem with 2 different motors.

I converted 2 7.5 motors... one a 1956 the other a 57.
one using the vacuum cap method.. the other filling the channel with hardener.

both motors start and run beautifully...

both motors when at high speed stall and need to be re primed with the fuel primer bulb to start.

they also both will stay running at high speed if I keep squeezing the bulb

ive used different tanks and lines to make sure it’s not the tank...

it’s like the fuel pump isn’t sucking fuel fast enough...

what am I doing wrong?

 

[F_R]

Well if it were me, I'd check the fuel pressure at the carb inlet and go from there. Fuel pump pressure gauges don't cost much, usually combined with a vacuum gauge. NOT to be confused with pressure gauges for fuel injection systems.

 

[racerone]

What pump did you use , a factory pump , something borrowed from a neighbor, an item from Amazon ??

 

[BlackoutBill21]

Both pumps are cheap Briggs and Stratton pumps

 

[jimmbo]

Just curious, what engines were these pumps off of?

 

[racerone]

Billy-----Blunt questions for you.------What pressures do the Briggs pumps operate at ?------How far is the Briggs pump from the fuel tank on a garden tractor ?----What is the lift capacity of the Briggs pump compared to a Johnson outboard pump.------Or do you think it does not matter ?

 

[F_R]

As I suggested, TEST the dadgum thing. Then you will know if it is working or not.

 

[BlackoutBill21]

The internet is full of dudes using brigs pumps... when I do it it’s wrong?? Does johnson omc make a 3 outlet inlet pump?? Where can I buy one. I will... blunt answers racer... why ask obnoxious questions... just get to the point... would you like me to buy a johnson Evinrude pump??? I will but as stated i used the intake manifold... so I need a pump that has 3 inlets connections one for vaccum one for fuel In and out... send me the link to that pump assuming that’s what you think my problem is and I’ll buy it

 

[BlackoutBill21]

Just curious, what engines were these pumps off of?

Pumps were brand new from amazon

 

[F_R]

Alternative test: Is the sintered filter element still in the glass bowl? If it is, remove it and see what happens. No money spent.

 

[BlackoutBill21]

Alternative test: Is the sintered filter element still in the glass bowl? If it is, remove it and see what happens. No money spent.

It is... I’ll take it off right now and find out

 

[racerone]

Obnoxious answer for you.----Find a 2 nipple pump.-----One inlet and one outlet.----Then modify the pulse port to accept a nipple.----Presto you have a 3 nipple pump.-------And Johnson / Evinrude do have 3 nipple pumps you just have to research what you can / can not use.------All very simple in my opinion.

 

[BlackoutBill21]

Same result

 

[BlackoutBill21]

I will research some more then and find the magic pump

 

[BlackoutBill21]

If I wanted to modify the pulse port to accept a nipple I would have started there... I went this route... the one numerous people send the you tube link to... soooo let’s answer the question at hand... I will search for a different pump

 

[BlackoutBill21]

How’s this?
https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/254329355239

 

[Tim Frank]

The internet is full of dudes using brigs pumps... when I do it it’s wrong?? Does johnson omc make a 3 outlet inlet pump?? Where can I buy one. I will... blunt answers racer... why ask obnoxious questions... just get to the point... would you like me to buy a johnson Evinrude pump??? I will but as stated i used the intake manifold... so I need a pump that has 3 inlets connections one for vaccum one for fuel In and out... send me the link to that pump assuming that’s what you think my problem is and I’ll buy it

The fact that neither motor works with the Briggs pumps at maximum fuel demand suggests strongly that there is insufficient fuel delivery (thanks Captain Obvious? ), and as some have suggested that is most likely a suction side weakness.

If it were me, I probably would have spent the $14- on the pump you have found on eBay.

BUT....first try raising the tank to a level at least as high as the fuel pump and see if that solves the problem. You won't be able to operate like that continually, but that will confirm the source of the failure.

Also as someone suggested, many Briggs pumps are mounted below the fuel tank (especially tractors) and suction side pressure is not much.

 

[Grub54891]

My thought, is the fuel tank vented?

 

[Crosbyman]

B&S pumps are good pumps… and should not be the cause of the problem. Some cheap B&S "look -a - like" pumps feel like garbage and probably are. look for ragged edges on the moldings .

One good official B&S pump I have is stamped MIKUNI ...go figure.

(BTW do a blow test on the pumps air flows OK in to out port NO air flows from the OUT to IN port )


the same pump is used on Kholer lawn tractors ... they are evrywhere


if motor works fine while pumping the bulb then the pump or the vacum pulse modification is inadequate ( I assume here that the carb is OK but recheck the inlet needle and float adjustment….. level with carb body …. then do a blow test on the carb)

I used the " sealed channel and removed the check valve" method (no rubber nipple)

The fuel tank pressure nipple behind the carb thus becomes the pulse supply to work the 3 nipple B&S pump

see picture of a B&S on a 5.5.hp works like a charm

 

[Tim Frank]

B&S pumps are good pumps… and should not be the cause of the problem. Some cheap B&S "look -a - like" pumps feel like garbage and probably are. look for ragged edges on the moldings .....
One good official B&S pump I have is stamped MIKUNI ...go figure......

I love B&S ....was not slagging them specifically.
An OEM quality pump would be fine I am sure, but it is often tough to know what you are buying on line.

My thought on raising the tank was that if it DID solve the problem temporarily, it would verify the OP's modification installation as OK and ID the suction ability of the B&S "type" pumps as the problem.