Checking fuel pump

[igneous]

Got the vapor separator off and cleaned filter/tank and bottom of pump... was a real PITA to get the 2 short hoses off the top of it. Is there any way to check it's operation off boat before I put it all back together? Any other things to check out besides float operation? Getting spark and gas to VS tank, just hoping to avoid having to buy a $600 fuel pump. Looks like you can't take hi pressure fuel pump apart and fix.

 

[WAJetboating]

Got the vapor separator off and cleaned filter/tank and bottom of pump... was a real PITA to get the 2 short hoses off the top of it.

Indeed it is. Suggestion: Replace those hoses with new high pressure fuel injection hose, using big loops so you don't have to duplicate those tight bends. They're tight like that because this engine was originally designed to live inside an outboard cowling, but inside your inboard engine compartment some extra hose length doesn't matter one bit. I did this when I rebuilt my fuel system and it worked fine. Rule of thumb is replace all fuel lines every five years so why not do that while you have it apart?

just hoping to avoid having to buy a $600 fuel pump. Looks like you can't take hi pressure fuel pump apart and fix.

Yes, it's a sealed unit. There are aftermarket replacements, though, so worst case you're not stuck.

The high pressure fuel pump (inside the VST) runs on 12VDC. If you want a quick test, just connect it to a battery and see if it runs. Once the VST is remounted on the engine, the manual lists tests all along the fuel system to determine if each major component is working... run those to confirm.

 

[igneous]

Thanks for reply WAJB. Good idea on the hoses, I'll cut those off and get a foot or so of fuel line. I used some permatex gasket sealer along w/original rubber gasket and have not hooked the battery back up to test pump and see how it sealed VST tank. If I have a leak(s), what sealer should I use?? The stuff I cleaned off w/min. spirits looked like silicone. Did some of the fuel tests, but want to find hi press. fuel pump soon. Need to do low pressure pump test, but elect. unit behind first filter clicks and sounds fine. Do you have to take powerhead apart to clean injectors?

 

[WAJetboating]

If I have a leak(s), what sealer should I use??

If you're talking about the lid on the VST, I found the standard gasket was sufficient. If you used anerobic gasket maker, I'd say it's probably more solid than OEM.

Do you have to take powerhead apart to clean injectors?

No. You remove the induction manifold from the front of the engine. The injectors are installed on the fuel rail which is inside the induction manifold, which is behind the ECU. In the process, it's easiest to remove the VST at the same time so you've already some of this work.

Once you have the induction manifold open, the injectors are then easily removed and reinstalled.

 

[igneous]

Yes, looks like the float keeps it below that level so should be no leaking. Going to get fuel hose today and test everything so I can order all I need at once. Final filter was nasty, but cleaned up fine--will order new one anyway. Good to know about injectors being easy, as that may be next. Thanks again for your help on this and all other threads....nice to have expert advice.

 

[WAJetboating]

Yes, looks like the float keeps it below that level so should be no leaking.

It's not just that. "VST" stands for "Vapor Separating Tank". When the high pressure fuel from the fuel rail comes back into the tank, it sees a drop in pressure that can cause it to flash to vapor temporarily. Thus you're looking for a gas-tight seal in addition to worrying about the actual fluid level within the tank. The normal gasket (and all those screws around the lid) takes care of that. Your addition of anerobic gasket maker is icing on the cake.

Going to get fuel hose today and test everything so I can order all I need at once.

Be sure to get injector rated hose, not just normal fuel line.

Final filter was nasty, but cleaned up fine--will order new one anyway.

If you're talking about the filter in the pressure regulator, yes - mine was probably 70% occluded too. But it's a metal screen, not fabric, so it can be restored to like new condition with solvent.

 

[igneous]

Yes, the vapors are channelled back to gas tank and vented out side. I couldn't get one of the pressure regulator screws out, so I need to work on that and try not to strip phillips screw. There's another filter in pressure regulator? Or are you talking about the final fuel filter under hp pump? I did find an old Merc bulletin about cleaning out hp fuel pump, but now can't find it. Basically said to fill VST with merc. fuel treatment thru inlet and let sit for 30 min, then get clear hose (to see fluid moving) and connect inlet to outlet of hp pump and turn on w/key to let cleaner run thru pump. Funny it didn't say anything about plugging existing inlet fuel line--what a mess!! I suppose any solvent would probably work also.

 

[WAJetboating]

Yes, the vapors are channelled back to gas tank and vented out side.

No, I'm talking about the high pressure fuel (in the injector rail) being returned to the VST. The sudden drop in pressure can cause the fuel to flash to vapor. The VST, which is found in one form or another on most fuel-injected engines, is the place where that gaseous state of fuel can recondense back to liquid. Without a VST of some sort, the high pressure fuel pump could end up attempting to pump gaseous fuel instead of liquid fuel - with poor results in the cylinders!

There's another filter in pressure regulator? Or are you talking about the final fuel filter under hp pump?

There are two filters associated with the fuel injection system. The first encountered by the fuel is the cylindrical one around the high pressure fuel pump. The second is a tiny little screen inside the pressure regulator, which sits on top of the VST and is the last thing in the high pressure system before the unused fuel rail gasoline is returned to the VST. I was speaking of the latter when I said mine was 70% occluded. You should get off that pressure regulator and clean that filter.

 

[igneous]

Ah, ok. Makes better sense now. I just tried starting and it bumped, as if not getting fuel. Going to change plugs and test hp fuel pump today and do what I said in last post to clean pump if it runs. Also wondering about the jet pump being locked up since I have no idea last time this thing ran, so don't need to cause more problems. I did read on another post that you want the engine running before putting running water into flush port. Don't want to flood engine. May need to get water hose and spray on impeller/pump just to get some lubrication under there. Going to get premium membership this weekend for more specific help ....great forum.

 

[WAJetboating]

did read on another post that you want the engine running before putting running water into flush port. Don't want to flood engine. May need to get water hose and spray on impeller/pump just to get some lubrication under there.

No, No, NO!!!! Do NOT run a Mercury SportJet without water running!

You have fallen victim to the "Rotax vs. Mercury" water debate. Rotax engines use the sequence "Engine on, water on, water off, engine off" because they are not self-draining.

Your Mercury engine, on the other hand, is 100% completely self draining. You do not need to "blow out" the engine or exhaust system after running the boat. More importantly, you MUST MUST MUST turn on the water first. There is zero chance for problems with the water running and the engine off. You can leave the water running for as long as you like. When you turn it off, the engine will drain automatically.

Note also that you don't have to treat the water cooling system for winter storage, no matter how cold it might get. No antifreeze is necessary (it would just drain right back out anyway!).

I hope I've been clear: NEVER EVER EVER run a SportJet without water running before, during, and after. Also, don't run it above idle except for very brief moments up to 2000 RPM if useful. Water from the hose does not go everywhere that water from the jetdrive does.

Finally, the jetdrive is always engaged. There is no "neutral" in the sense that it disconnects the engine from the jetdrive. If the engine is able to crank, the jetdrive is turning - unless you have completely stripped the bevel gears in the jetdrive.

Lubrication of the jetdrive is handled automatically by connecting and running the water hose. You'll see water pouring out of the jetdrive intake and exhaust, as well as the muffer exhausts.

 

[igneous]

Good to know....separating forums to merc and rotax should eliminate confusion. So you're saying I can go hook up hose and run water thru it basically anytime, running or not for any length of time? Boat in garage now, but could still do it somewhat.

No problem with starting yet, as I've been keeping lanyard off anyway doing preliminary checks w/fuel delivery.

Anyway, got the vapor sep. off yesterday to clean press regulator filter and stripped 1 screw. Had to JBweld a screwdriver bit to the damn thing, so maybe I'll have better luck today. I did hook up clear hose off hp fuel pump outlet and it did push fuel when cranking, just not sure if enough pressure. Need to do fuel pressure test to verify.

Also ordering new fuel hose to replace all...ones I can read say "2001", so I'm thinking
that may be year made? If so, it's original hoses that are 10+ yrs old. Isn't that a 5/16
ID fuel line with 3/4" OD?
Another quick Q...Can using a drill (12v cordless) ignite gas vapors in engine compartment? I found the bottom VST mount bolt had been broken off and cannot remove. Need to drill out and re-tap.

 

[WAJetboating]

So you're saying I can go hook up hose and run water thru it basically anytime, running or not for any length of time? Boat in garage now, but could still do it somewhat.

Exactly. Water is OK anytime, engine running or not.

Also ordering new fuel hose to replace all...ones I can read say "2001", so I'm thinking
that may be year made? If so, it's original hoses that are 10+ yrs old. Isn't that a 5/16
ID fuel line with 3/4" OD?

Yes, 5/16 ID fuel line.

Another quick Q...Can using a drill (12v cordless) ignite gas vapors in engine compartment? I found the bottom VST mount bolt had been broken off and cannot remove. Need to drill out and re-tap.

YES. Be careful. I recommend opening all hatches and letting it stand for a while. Brushed DC motors give off sparks; theoretically brushless ones don't, but who knows what is in your drill motor?

 

[igneous]

Did finally get the pressure reg. off VST, damn screw was so tight it was bent. Where is the filter? All is see is a small hole and O ring it sits on and inside it's clean as can be. Is it in the VST lid?
Yeah, I need to find out if my old dewalt DW980 is brushless or not. Good excuse for a new 18 or 24 volt anyway...be a PITA to drill out ss bolt, even w/cobalt bit.

 

[WAJetboating]

Did finally get the pressure reg. off VST, damn screw was so tight it was bent. Where is the filter? All is see is a small hole and O ring it sits on and inside it's clean as can be. Is it in the VST lid?

No, it's inside the inlet fitting on the pressure regulator. If you remove that right angle inlet fitting, you'll find an o-ring and a metal screen. All unused fuel coming back from the fuel rail passes through this screen. In other words, the fuel+oil mix is often filtered multiple times by this screen. It gets really dirty, but cleans up quite nicely.

If you have the November 1999 version of the engine service manual, page 3D-59 has two exploded diagrams of the regulator. In the upper diagram, the filter is item "b". The manual instructs you to "Inspect fuel filter for debris. Clean with solvent as required."

 

[igneous]

Ok, I'll look at that today. Had to get long replacement screw for upper housing since I chewed up original getting it out and will replace w/hex head bolt.

 

[igneous]

I did get the tiny little screen out of press regulator housing and it was clean--prolly because I soaked/flushed tank with min. spirits. About many feet of hose do I need to replace all that has fuel running thru it?

 

[WAJetboating]

I did get the tiny little screen out of press regulator housing and it was clean--prolly because I soaked/flushed tank with min. spirits.

OK, glad to hear it. Mine was filthy but cleaned up nicely too.

About many feet of hose do I need to replace all that has fuel running thru it?

I don't remember how much I purchased but it isn't hard to determine. I replaced everything, starting at the fuel tank, except for the hose running to the vent on the side of the hull. Just roughly measure the longer pieces (tank to inline filter, return lines, etc.) and estimate the shorter ones (across the front of the engine from pump to fuel/water separator to VST, etc.). All of that needs to be USCG rated 5/16 hose. There is a type A and a type B; one is for exposed (outboard) installs and the other is for enclosed (inboard) applications. I believe you want type A, just copy what is on the current hose.

The fuel line that connects to/from the fuel rail must be fuel injector hose. It's much more expensive on a per-foot basis. The ones that come stock on the engine are bent and twisted into a specific shape that is impossible to match with stock hose without kinking and thus reducing flow, so I just installed two loops of approximately 8-10 inch diameter each and let the hose find its natural bend radius. This is perfectly acceptable, since the high pressure fuel pump and the pressure regulator maintain the proper pressure in the system regardless of its slightly increased volume. If we presume those loops are 12 inches diameter each, you need about six feet of 5/16 injector hose.

A word of caution: It is devilishly difficult to cleanly remove the injector hose from the fittings on the fuel rail and VST/regulator. I always had to cut mine off. Be careful you don't nick the fittings, and despite how hard it is to remove them ALWAYS use full stainless hose clamps. They do make "special" injector hose clamps but normal screw-type work fine.

 

[igneous]

Yes, I found some good 5/16 Trident hose type A-15 w/barrier lining at MMI marine.com and it's only $1.53 a foot. Yes, those were the PITA I described in my first post....very tight. I need to examine nipples and see if I need to sand alittle if I nicked them. I'm sure MMI will have injector hose also, and prolly need to look at exhaust hoses while I'm at it. I have a good supply of ss clamps.

 

[WAJetboating]

I have a good supply of ss clamps.

As I said, standard stainless clamps are fine. "Fuel injection" in this case is under 40 PSI. We're not talking direct fuel injection (like a diesel) here. That's where the special injector clamps start to matter.

 

[igneous]

Been out of town for a week and just got back and joined premium membership and started post there. There has to be an aftermarket replacement for the hp fuel pump that don't cost $600. Also, any relay or fuse to check before buying fuel pump?

 

[WAJetboating]

Been out of town for a week and just got back and joined premium membership and started post there. There has to be an aftermarket replacement for the hp fuel pump that don't cost $600. Also, any relay or fuse to check before buying fuel pump?

Yes, there are aftermarket fuel pumps that are drop-in replacements. I can't remember who right now, but I found at least two sources when I was searching about a year ago. Do a Google search using the Mercury part number, and abbreviations thereof. That's probably how I found it.

I believe there is an on-engine fuse for the fuel pump. There's a group of three(?) fuses on the engine, and I think one of them powers the HPFP. Check the manual. Remember you can also disconnect the HPFP power leads and check for 12VDC when the keyswitch is in the "Run" position.

 

[igneous]

I found replacement pump for $415 from www.speedncustommarine.com . They also have them on ebay. I looked for the fuse block on the engine and couldn't find it, but did see the one on the first electric fuel pump. Where are they on the 240 hp motor? I did check at the pos. terminal on the HPFP and had 12.6V, so I assume the fuse is ok. All else seems ok since the VST is getting fuel. Did start changing all the fuel lines and the new ones are much easier to remove and put on.

 

[igneous]

Another question...where is/are the anti-syphon valve(s) in fuel lines?

 

[igneous]

Got the hp fuel pump installed and got boat out of garage this weekend. Put the hose onto it and it fired right up. It did fine, actually very quiet and didn't smoke that much. The large exhaust hoses are soft and one is sort of flattening, so I need to replace them. What size wet exh. hose are these and are they suppose to be rigid?

Also removed original hydrosurge grate and will order ss 11 tine this week. Couldn't believe that no tines were broken! Need to also get pump oil checked and prolly changed, since I have no maintenance history on motor or pump. Anyone have a link to the oil pump used to do this? Don't want to waste my time without the right tools!

WaJboating, thanks again for the abundance of knowledge you've shared on this site.

 

[WAJetboating]

The large exhaust hoses are soft and one is sort of flattening, so I need to replace them. What size wet exh. hose are these and are they suppose to be rigid?

Mine are exactly the same way. My port hose is "sort of flat" (kinked) at the bend. It's always been that way since the day I got the boat. The hoses haven't changed in their shape nor rigidity so I haven't bothered to replace them. Up to you if you think it's an issue. I'd buy the OEM hoses since, like the high pressure injector hose that comes on the engine, they may be properly pre-shaped for that bend... I'm not sure off-the-shelf exhaust hose will make that bend without kinking. (BTW, I've tried various methods of un-kinking the hose as it goes around that bend but nothing has worked.)

Need to also get pump oil checked and prolly changed, since I have no maintenance history on motor or pump. Anyone have a link to the oil pump used to do this? Don't want to waste my time without the right tools!

Any Merc shop will have the pump. It screws in place of the lid on the lube bottle. Yes, you should do a complete "winterization" service on this jetdrive if you don't know its history, especially since you're heading into the busy season. That means both front and rear lubes, plus inspecting impeller/wear ring clearance, etc.

Sounds like things are coming together - congratulations!