Pressure build up in fuel system

[Edvis of Export]

Recent work: placed new scavenger tube from carb to manifold (there was a leak), replaced carb flange gasket (there was a leak).
New problem: won't turn over due to fuel starvation symptoms. On draining the fuel filter/water separator, a burst of fuel under pressure came from the filter. Tried to turn it over: same fuel starvation symptoms. I then checked the inline fuel filter and again fuel under pressure was discharged as the hose was detached.
Anyone ever experience this type of fuel pressure buildup and fuel starvation symptoms?
Any causes for it?
Thanks,
EoE

[Dave Neptune]

EoE, where is your fuel pump in relation to the build up? There should be no pressure before the pump, only after the pump and to the carb.

You may have a blockage but a bit of info on the routing of your fuel system would be most helpful in diagnosing where the restriction/blockage is.

Dave Neptune

[Al Schober]

Any chance the inlet/outlet of the fuel pump got switched?
What happens if you remove the cap at the fuel fill?
Love these strange ones... (grin)

[Edvis of Export]

For Dave
The fuel delivery route is:
1) Tank
2) Fuel line w/ primer bulb
3) Separator/filter
4) Fuel line w/ inline filter
5) Electronic fuel pump
6) Carburetor

Inline filter & separator both less than 1 year old.
Starting was normal before I changed scavenger tube & carb flange gasket.
Thanks.

[Edvis of Export]

For Al:
Almost 99.9% sure the inbound/outbound fuel pump lines did not get switched but that's a good idea & will double check.
Opened gas tank cap and did not notice anything unusual like suction sound.
Thanks.

[joe_db]

Get rid of the primer bulb. Huge safety hazard

[JOHN COOKSON]

Need A Clarification

New problem: won't turn over due to fuel starvation symptoms. On draining the fuel filter/water separator, a burst of fuel under pressure came from the filter. Tried to turn it over: same fuel starvation symptoms. I then checked the inline fuel filter and again fuel under pressure was discharged as the hose was detached.
Thanks,
EoE

Does the engine not turn over with the starter? Or does the engine turn with the starter but not start? Does fuel pool a bit in the carburetor after a period of no start cranking? Did you get the choke adjusted correctly so it closes all the way after you replaced the flange gasket?
Maybe the primer bulb is making some sort or back pressure in the fuel system - this is truly just a guess.
Have you been keeping the inlet valve to the raw water pump closed while you've been no start cranking?

TRUE GRIT

[Edvis of Export]

For True Grit John
Does the engine not turn over with the starter? NO STARTER IS OK.
Does the engine turn with the starter but not start? YES.
Does fuel pool a bit in the carburetor after a period of no start cranking? NOT SURE - GOOD IDEA WILL CHECK.
Did you get the choke adjusted correctly so it closes all the way after you replaced the flange gasket? GOOD IDEA WILL CHECK
Maybe the primer bulb is making some sort or back pressure in the fuel: POSSIBLE
Have you been keeping the inlet valve to the raw water pump closed while you've been no start cranking? YES IT WAS CLOSED

Thanks for your input
EoE

[Edvis of Export]

For Joe DB,
Thanks for advice.
EoE

[joe_db]

Those squeeze bulbs were NOT designed for enclosed engine rooms. They do not meet fire standards and they spring little leaks when they get old. The one on my dinghy squirted me right in the face one day

[Dave Neptune]

EoE, if the hoses are not switched there is really only one way I can think of the suction end of the system to pressurize and it is unlikely. Could you vent be plugged(?) causing a build up inside the tank. If this were so it would be a bunch of fuel running out and I mean a bunch.
If the lines are backwards the pump would pressurize anything between it ant the (get rid of it) squeeze bulb because of the check valves it contains.

Dave Neptune

[Bingy]

in line filter

I switched my in line filter from before pump to after and then to carb.
Also moved electric fuel pump to bulkhead.