FUEL PUMP vs ANTI-SIPHON VALVE

mark1190 · **Posted:** Fri Jul 10, 2020 10:31 am

Thanks in advance for Help! My issues continue with what appears to be fuel-delivery to my engine.

1996 FOUR WINNS 205 SUNDOWNER
5.1 EFI Engine
Volvo Penta

Even more of a conundrum:

Where on a '96 Four Winns 205 Sundowner is the anti-siphon located? Would it be under the floorboard close to the engine (there are screws I can take out and lift the board?) Is the fuel tank under there? The engine compartment is walled (bilge) so I see no gas tank. Should I just replace them both (anit-siphon AND fuel pump)? IS this a DIY or does my guy need to do it?

Any help is welcome.

Thanks!

Mark

LouC · **Posted:** Fri Jul 10, 2020 12:14 pm

It is right on the fuel tank, the barbed fitting that the hose from the pump connects to. It was a problem on mine too. The engine would start, run fine and rev fine in neutral but would not plane out the boat. Our former mechanic found this and replaced the cheap aluminum one with a better quality brass one (Evinrude/Johnson brand) and this was in 2004, no problems relating to this since....
Be careful trying to remove this, they can be stuck on...take your time be patient...

mark1190 · **Posted:** Sat Jul 11, 2020 4:12 pm

Thank you Lou. Is this a DIY for a beginner (I tinker some, I fix chainsaws and sprinklers, but this is uncharted waters)(pardon the pun). I am thinking I might replace the fuel pumps, too. Last problem was 10 years ago.

I lifted the floorboard of the SUNDOWNER 205.

Found the gas tank. The Anti-Siphon is right on top. The tank is FULL. (is that a problem?)

This is what she looks like when 100% and on the water (Friday Harbor, WA)

Mark

LouC · **Posted:** Sat Jul 11, 2020 7:36 pm

Boat looks great!
If the valve will come loose it’s not a hard job. Use a bit of penetrating oil let it soak in first. If it won’t come don’t force it esp with the tank being plastic.

mark1190 · **Posted:** Tue Jul 14, 2020 11:32 pm

Lou, thank you. Valve not exactly cooperating so I am having my mechanic do it. Also looking at buying fuel pump(s). A year ago it was you (surprised) who mentioned CARTER pumps. I got the serial number off the side of the fuel pump on there now. 3858261. Volvo Penta Elec Fuel Pump (Low Pressure) for carburated engine. Mine is FI. DOes it matter?

Your CARTER suggestions were:
CARTER P60965
CARTER P61171

Either one work? An where would the "High" Pressure pump be? I replaced that about 8 years ago. Might as well do both. Sorry for really beginner questions.

Thanks, Lou.

MArk

LouC · **Posted:** Wed Jul 15, 2020 10:20 am

yes it matters, the electric pump for a carb system puts out 4-6 psi. The EFI pumps put out much more pressure like 45 psi. Also the pump unit may be made up of a low pressure and high pressure pump. Take a look at the Volvo parts diagram and see what it looks like. BUT, before spending the $$$ do the anti siphon valve, and then measure pressures. If it's good no need to buy a new pump. Have you dumped the fuel filter out and taken a look at the contents? I do this every year as my boat has the original (32 year old) gas tank.
The other test you can do (but be careful with the hook up) is to pick up a small outboard gas tank. Hook up your fuel line to that and see how it runs. This rules out problems with the tank, anti siphon, tank vent and tank fuel pick up.

to find out where the pump is and what it looks like put your V/P engine model # into a VP parts catalog, it will start with 50 (5 litre engine) 57 (5.7 liter) or 58 (5.8 liter). Then there is a VP code which is inscrutable but indicates if it has efi or carb etc.

http://www.volvopentastore.com/Engine-P ... ore_id.366

looky here...

LouC · **Posted:** Wed Jul 15, 2020 10:32 am

http://www.volvopentastore.com/Fuel-Sys ... _id.782706

if you have a Ford 5.0 engine (Ford has the distributor in the front, GM in the rear) it could be this one but you must match up your model # for sure. You can see one pump is the one in your pic next to the Power steering pump) part #41 (lower pressure pump) the other is the high pressure pump part # 19. When you see the prices ($700+ for both) if you can get them direct from Carter you can save money but make sure you need them in the first place.
What kills EFI pumps:
bad design for a while Carter was painting the inside and the ethanol in the fuel broke down the paint, supposedly this issue is long past though
fuel restrictions, ie clogged vent, anti siphon valve or fuel pick up in the tank
bad/corroded terminals on the electrical contacts for the pump

this is why I prefer a simple old school engine with a carb I can rebuild for $50 and a mechanical fuel pump I can change for $85. Can't beat it but yes EFI runs better esp when cold.
I grew up in the 60s-70s and all my cars had carbs. So I am well versed in them.

https://mancavemechanic.com/
here's another option, I have no direct experience but some report good experiences.

mark1190 · **Posted:** Sat Jul 18, 2020 4:49 pm

Good progress, I hope, on tracking down the problem. The 24+ year-old *aluminum* anti-siphon valve may be the culprit.

Here is a look INSIDE -- a little piece of plastic got sucked up into it. I can barely blow through it.

Replaced with brass valve. Fuel filter was clean, no debris. Replaced it just to be sure.

Judging how difficult it was to get air to pass through the anti-siphon, I am hoping that during the very few hours I was dealing with this issue that I did not stress out the fuel pump too much. It runs FINE at idle with the muffs on. But I need to test it under a load. That will happen tomorrow evening when the docks (and river) around here clear out.

Mark

LouC · **Posted:** Sun Jul 19, 2020 10:58 am

Great find and see how checking each little thing, really helps.
My mechanic replaced mine in 2004 with the brass one and I have not had another problem with it since then. I have rebuilt the carb 3 times over 18 years and replaced the old mechanical fuel pump once.
With electric fuel pumps you really want to make sure you have no restrictions in the fuel flow and your electrical terminals are clean and tight. That's what kills electric pumps.
The reason why marine electric pumps don't last like is vehicles is this:
in a vehicle the pump can be in the tank, where is pushes gas to the EFI system instead of pulling it and being in the tank in gas keeps it cooler
A marine system can't be set up that way due to the possibility of fuel leaks under pressure causing a fire risk in the engine compartment so it must pull fuel from the tank which is harder on the pumps. This is why so many people have trouble with electric pumps on both Volvos and Mercs.
Mechanical pumps just plain last longer, as in 30 years in my case! But that's what the newer engines have so this is what you have to do to make them work....

mark1190 · **Posted:** Sun Jul 19, 2020 9:25 pm

Well, Lou, the sea trial was an abject failure. Startup absolutely fine. Troll absolutely fine. Pushing water at 2000 RPM absolutely fine. When I tried to come out of the hole, barely enough power to get it to start to plane. The Engine pitch sounded normal for just a few moments, but then would change to lower rpm, then jump higher, then lower. When it would drop an octave you could feel a loss of power. Near the end of the attempt I was able to get it to plane but the changes in noise pitch (very sharp and clear) would not keep the boat on top and eventually it settled back into the water. Two people were on board. Not impressive. I shut it down and pulled it out of the water.

Fuel pump(s) next? I think we'll pressure test them tomorrow or Tuesday. Mechanic was CERTAIN the anti-siphon was it. Not. :evil:

Mark

zims1993 · **Posted:** Mon Jul 20, 2020 5:50 am

Your high pressure pump is located at the back of the engine on top of the bellhousing area where the fuel cooler is also. Here is my post about our '93 5.0 EFI when I replaced the fuel pumps. You do not have the fuel pump assy listed above from mancavemechanic.
My pumps had the Carter number stamped right into them, which I purchased replacements from Rock Auto. Do a simple fuel pressure check at the fuel rail with the vac line off the fuel pressure regulator should be about 39psi, typical Ford fuel pressure.

viewtopic.php?f=11&t=23389

Also will the engine free rev past say 2500 rpm, if not one of the SLOW sensors could be faulty causing your issue?

LouC · **Posted:** Mon Jul 20, 2020 9:23 am

Good info above, pressure check next... if not good see if you can get the pumps from Carter (use the Carter part #s and then order from Rock Auto, Jets or Summit Racing). I did the same thing when I needed a Carter mechanical pump a couple of years ago; OMV wanted like $240 for it and I found it on Jegs or Summit for like $85. The other thing is the fuel injectors themselves sometimes they need to be cleaned and flow tested.

mark1190 · **Posted:** Mon Jul 20, 2020 10:55 am

In driveway or on the dock the engine will rev past 2500 pretty decently. I do not hear any engine whine change at that level. But with a load on it, that is what is making the difference, I *do* hear the chance in engine sound pitch mostly at higher rpm (like 3000-3500+ rpm) much more clearly and that's when performance suffers. Under load you definitely feel the boat suffer the momentary loss of power, then back up again, then back down. In fact, with WOT I really couldn't see the RPM's go past 3000-3500 under load.

Almost 10 years ago I had to replace the high pressure pump. The symptom then was "no start" - it just wouldn't turn over. This one is a little more stealth. Good start, but good low rpms, bad high rpms.

Last time I had a symptom like this (the engine changing pitch and power back and forth) I was running WOT out in the sea, but finished the trip (another 30+ miles) with stops in between. It was my last run of the week. When I got home I was told the engine blew a valve and scorched the chamber. I am trying to avoid that scenario all over again! LOL!

Thanks, Lou, for all your input.

LouC · **Posted:** Mon Jul 20, 2020 3:02 pm

You’re welcome and keep at it I hope the solution will quickly found!
Just put mine on the mooring today, we’ll see how she runs this season. I had to some Fiberglas repairs that held me up a bit the I was waiting to get my bottom paint done. That is one job to don’t do, I do just about everything else!

LouC · **Posted:** Tue Jul 21, 2020 3:44 pm

sometimes I'm glad I still have these:

https://www.dropbox.com/s/zu1hut15udcnx ... d.JPG?dl=0

the venerable Quadrajet, best carb ever built (IMHO) can be rebuilt for $50 with old school skills (which I have)
and a simple mechanical fuel pump you can buy for $85

https://www.dropbox.com/s/h0obipq3ccy4s ... 3.jpg?dl=0

www.iFourWinns.com

FUEL PUMP vs ANTI-SIPHON VALVE

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