mercruiser 260 help

[85_celebrity]

Re: mercruiser 260 help

Ok I pulled the anti-siphon valve off and tried to blow through it. I can blow through it but I have to blow really hard to get any air to flow through it and it also makes a shuttering noise while I blow through it. Does this sound normal and if it isn't normal where can i go about getting one of these?

Thanks so much guys this would have had me on the verge of selling the boat if it wasn't for you help.

 

[Haut Medoc]

Re: mercruiser 260 help

"Hard" is a subjective term......
It does sound like it needs to be replaced though......​

 

[85_celebrity]

Re: mercruiser 260 help

where can i obtain one of these. I looked on boaters world and didnt see one. Is this something that i could just go to a parts store and pick up or is a marine specialty fitting?

 

[1730V]

Re: mercruiser 260 help

The anti siphon valve is a marine part. Boat dealers should have them. You can run without it for TESTING.

You have an air leak somewhere. Your carb should not drain.

 

[85_celebrity]

Re: mercruiser 260 help

Ok I have looked all over and cannot find the valve at any of the local marine supply places that are local. we have a boater's world and an overton's within driving distance but no marina that I can find. i have looked all over the internet and found what i think is the right part ( tempo part number 260030) but I can't seem to find anyplace where it isn't back ordered. If anyone knows where I can find this please help.

 

[searay3]

Re: mercruiser 260 help

IBOATS Mall :http://www.iboats.com/Fittings_and_...d.238200--page_number.3--search_type.category....
not sure about the backorder status..

 

[180shabah]

Re: mercruiser 260 help

The anti siphon valve is a marine part. Boat dealers should have them. You can run without it for TESTING.

You have an air leak somewhere. Your carb should not drain.

An anti-siphon valve that is clogged and does not seal, will allow gravity draining of your fuel system back into the tank.

 

[180shabah]

Re: mercruiser 260 help

IBOATS Mall :http://www.iboats.com/Fittings_and_...d.238200--page_number.3--search_type.category....
not sure about the backorder status..

I think we are gonna need a new sticky....

"Looking for parts? Try the TOP OF THE PAGE"

 

[85_celebrity]

Re: mercruiser 260 help

I am sorry, I am very new to this forum and didn't see the headings for parts.

 

[Don S]

Re: mercruiser 260 help

The purpose of the anti siphon valve is NOT (NOTICE, I said NOT) to prevent gas from your fuel system from going back into the tank. That is the purpose of the check valves in the fuel pump.
There seems to be a lot of misconceptions out there of what the ANTI SIPHON valve is for. Most are wrong. It's ONLY purpose is to prevent gas from siphoning out of the tank and into the bilge should something go wrong.

 

[85_celebrity]

Re: mercruiser 260 help

I went ahead and ordered a new one it may not be the cause but the way I look at it the boat is 20+ years old a new part is not going to hurt it.

 

[85_celebrity]

Re: mercruiser 260 help

Oh yeah BTW I have a question about the fuel test DonS recommends. First the snap on gauge the you refer to is for EFI and I have a carb set up didnt know if it would make a difference. Also there is and unused port on the water separator and i was wondering if I could tap in to that.

 

[Don S]

Re: mercruiser 260 help

I went ahead and ordered a new one it may not be the cause but the way I look at it the boat is 20+ years old a new part is not going to hurt it.

AKA: Throw money at it, and hope for the best.

 

[85_celebrity]

Re: mercruiser 260 help

AKA: Throw money at it, and hope for the best.

No I definitely don't just throw money at it and hope for the best, but this fitting looks a little rough and it was less than $20 so replacing it isn't a big deal and is one less thing to break later on. I did have to order it so it is going to take a few days to get here can i just find a brass fitting like it and use it or will it cause imminent death?

 

[180shabah]

Re: mercruiser 260 help

An anti-siphon valve that is clogged and does not seal, will allow gravity draining of your fuel system back into the tank.

The purpose of the anti siphon valve is NOT (NOTICE, I said NOT) to prevent gas from your fuel system from going back into the tank. That is the purpose of the check valves in the fuel pump.
There seems to be a lot of misconceptions out there of what the ANTI SIPHON valve is for. Most are wrong. It's ONLY purpose is to prevent gas from siphoning out of the tank and into the bilge should something go wrong.

I understand the purpose of the valve, but it doesn't know what it is SUPOSED to do. It just closes when there is no vacuum. Gravity don't care if the fuel line is going down to the bilge or up to the carb. If the A/S valve doesn't close, fuel will flow.

For the record, I don't think this is causing his problem, but he asked how where it was and how to ID it.

 

[wire2]

Re: mercruiser 260 help

I am pretty convinced about changing the carb, doing away with the quadrajet and stepping up to either a holly or an edelbrock.

"...stepping up..."?
You seem to be down on Q-jet for some reason?
Mine has been extremely reliable for many years. The 7/8" primaries give very good efficiency at low to mid power range, the 2?" secondaries bring on the hole shot.

If yours has a hose barb with a clear tube going back to the fuel pump, it is a marine carb.

I have a very similar set up, a Glastron 19 ft bowrider with 5.7/260. I turn a 14? x 21 stainless for high 50's with 2 people & gear in boat.

If you've verified proper fuel pump pressure, I'd be inclined to briefly experiment with ignition timing under load. With engine cover off, mark the position and loosen the distributer clamp a bit, and have someone drive it while you adjust a few degrees both ways. You'll know instantly if that's an issue.

 

[85_celebrity]

Re: mercruiser 260 help

I haven't had good luck with Q-jets on cars before and this one on my boat is giving me fits. I want to switch it to something I am a bit more familiar with, that is the main reason i want to go with a holley or a edelbrock. I don't see any clear tube coming from the carb, I know I ask this a lot but I maybe missing it so where exactly is it?


I am going to perform the tests that DonS recommends as soon as I can get a definitive answer about the gauge the I need to get or borrow.

We have tried messing with the timing while under load and it didn't seem to make any difference. What are the chances that this boat is just simply overpropped?

 

[Haut Medoc]

Re: mercruiser 260 help

I haven't had good luck with Q-jets on cars before and this one on my boat is giving me fits. I want to switch it to something I am a bit more familiar with, that is the main reason i want to go with a holley or a edelbrock. I don't see any clear tube coming from the carb, I know I ask this a lot but I maybe missing it so where exactly is it?


I am going to perform the tests that DonS recommends as soon as I can get a definitive answer about the gauge the I need to get or borrow.

We have tried messing with the timing while under load and it didn't seem to make any difference. What are the chances that this boat is just simply overpropped?

If you can't get the proper WOT out of that engine with a 14x19, then something is amiss.....
14x19 is not overpropped for that engine....

 

[85_celebrity]

Re: mercruiser 260 help

Ok thanks.

 

[Don S]

Re: mercruiser 260 help

Here is a copy and past of the second paragraph from this thread http://forums.iboats.com/showthread.php?t=167561

The Snap-On fuel gauge mentioned below is not a necessity; any good fuel pump pressure/vacuum gauge will work or even a single vacuum gauge. I have one from NAPA that works fine for the tests.