fuel delivery

[gjs4]

hello all.

I have an 80's sylvan..with an early 80's Johnson 70-hp outboard. This boat has been to the marina twice for repairs since my ownership a year ago....they replaced the exterior fuel line and primer ball...cleaned the cabrs..fixed a broken midjet tube...it has yet to run decent for me...today it wouldnt even start....i switched fuel line over to my kicker motor (a 60's Johnson 18hp) which has always started in 5 pulls.....it took close to 50 and full choke... to keep it running we had to pump the primer ball....it would get hard and then slowly lose pressure....took the boat home and checked out the existing (non replaced line) from the transome metal )double sided barb fitting) to the factory tank....it looked OK...but we bypassed it anyway and ran the fuel line directly to the tank....(so it went tank>hose>primer bulb>hose>fitting>motor......)...the bulb still wouldnt get rock solid.... the fitting secure the hose to the bulb and barb are super tight (fixed banding clamps)..the hose and bulb are brand new...the tank is half full..... I pulled the fitting (threaded male nipple to 90 with plastic pickup tue and small metall intake/screen mesh...had gas 3/4 way up it)- that looked fine..... what can I do now? I am ratehr sure the probem is between the fitting that connects the fuel line to the motro and the tank pickup...I am not looking to buy another fuel line steup (or tank)..but I have a useless boat......when it did run last year it was starving for fuel (especially before repairs)...the vent is not obscured......I am losing my mind here.....any and all help WILL be graciously appreciated...thanks

-garrett
garrettt@rochester.rr.com

 

[Barnacle_Bill]

Re: fuel delivery

It sounds like you have a problem with the pickup tube in your tank. Borrow a portable tank from someone and run your line to it and try it.

 

[ezeke]

Re: fuel delivery

The first visible outgoing hose connection on a fuel tank usually contains a so-called anti siphon device.

It is a spring loaded ball bearing that closes the fitting when there is no suction on the line.

The problem with the little jewels is that they get stuck and don't allow much flow.

Coast Guard regulations require such a device, but there is also one in your primer bulb.

 

[rickdb1boat]

Re: fuel delivery

Some reading pertaining to anti-syphon valves that may help..

http://marinemechanic.com/asof-8-29/antsiphon.htm ] Click Here [/url]

 

[OBJ]

Re: fuel delivery

I'm assuming that the work done was on the 18hp and not the 70hp? Your post at the beginning tends to point to the 70hp but your having problems with the 18hp?

It could also mean that either the diaphram in the fuel pump has ruptured or the float may be stuck and not closing the needle vlv.

Did you notice any fuel sheen on the water?

 

[ezeke]

Re: fuel delivery

Glad that you referenced that, Rick, because it reminded me of one other thing.

The newer fuel formulations have made some of the old anti-siphon fittings obsolete; the safest bet is to replace the fitting.

 

[gjs4]

Re: fuel delivery

The 70hp is the problematic one..the 18 is my tried and true runner....the reason i brought up the 18 is to mentioned it would not run (vouching that it is problem free) unless the primer ball was pumped while the engine was running...

I know the fitting has remained the same despite the multiple repairs...it will be replaced ASAP.

I noticed a crack in the tank vent hose (~1" rubber).. i plan on rpelacing that too...

In terms of the jet stuck....those carbs were "professionally" maintained/repaired twice in the past year...although this may be an issue...there is a fuel delivery problem (thats why i mentioned my 18 wouldnt run worth a sack of fertilizer)....

 

[steelespike]

Re: fuel delivery

If I understand you it appears you are having trouble with your tank or hose to your 70hp and the same tank/hose is giving the 18 trouble.
If the motor is running the bulb will get softer as the motor uses gas.If not then it should remain hard.If it collapses then there is a blockage between the tank and bulb or the vent is plugged.
One common place to give trouble is the connector at the motor and or tank.Sometimes will leak air but not gas.As suggested test with another tank and hose.Then the hose alone.

 

[gjs4]

Re: fuel delivery

Bought a brand new fuel line from tank (inc fittings) to the motor (includig the primer bulb)....hopefully this is the cure

 

[DJ]

Re: fuel delivery

Bought a brand new fuel line from tank (inc fittings) to the motor (includig the primer bulb)....hopefully this is the cure

That won't help you if the anti siphon valve is stuck closed, or partially so. Or, did you get a new anti siphon valve too?