Article [11] ST1100 - Fuel Pump Replacement

Installed the Spectre fuel pressure regulator set at 2.5 psi


Used some silicone tubing to get it all together, hope it'll stand up to the fuel. Any thoughts?

I've been told that the silicone tube is not good to run raw fuel through. After a time it will swell and loosen. The silicone tube is really designed for engine vacuum applications and lasts a long time for that purpose.

Dan

bdalameda said:

I've been told that the silicone tube is not good to run raw fuel through. After a time it will swell and loosen. The silicone tube is really designed for engine vacuum applications and lasts a long time for that purpose.

Dan

Click to expand...

That's my take too!

I can tell you from first hand knowledge that RTV and gas are not compatible. I think the hose gets soft and gooey after time.

I read that article on the web a while back about replacing the pump for a Gold Wing w/carbs with a Delphi pump ( that isn't made anymore ). I managed to find two at Rock Auto on close-out last year for $17 each, so now I have a spare.

My stock pump was working OK, but I wanted to replace it before it started acting up or failing. Being all plastic, it seemed to me it would fail eventually and it was 14 years old.

Here is a pic. It was easy to modify the stock bracket. I also removed the vacuum shut-off valve and subbed a simple check valve from McMaster-Carr. I think that would also help reduce pressure somewhat since I think the Delphi pump may put out more than 2-3 psi. It flows about 4 times what the stock pump does. My mileage seems basically unchanged - about 43 mpg @ 78-82 MPH. I have about 10K miles with it, so far.

I solved my mileage problem for the current trip by bringing lipSTick instead of STick. Highn 40s at highway speeds. And, she's running STick's stock tank and pump with over 200,000 miles on'em. Even with the "restrictor" valve in place, STick returned only 30 MPG on her last tank toward home at first-of-the-month. That was at elevated speeds tho.

Jeez. Failed fuel pump on Monday. This was/is STick's original pump, 200,000 miles when I transferred it to lipSTick and many thousand miles since then. Had just exited an EXTREME down power when she "ran out of gas." First suspicion was wet ignition, given the recent rain, but it was the fuel pump. Again.

That makes all three of my OEM pumps have failed while on the road. LipSTick was first, with about 155,000 miles on her OEM. Added the aftermarket auxiliary pump to get home. Replaced the original with the pump out'a ReSTored (which had been setting for a couple years.) All was good for only a few hunnert miles when that one quit.

Next try was to replace lipSTick's entire tank assembly with the one out'a STick, working fine at 200,000 + miles. That's the one which just gave up. Still had the aux. pump installed but needed to rewire it. Made it the rest of the way to The STrayCatt Mansion in Aurora, seems to be running normally.

(STick is now running one of the after market pumps I purchased last year, made 11,000 miles on it this spring but gas mileage was/is terrible. need to sort that when I get home. She had run for a few hunnert miles a rebuilt stock pump but it didn't last.)

Three failed OEM pumps (plus the failed pump out'a Will England's wreck). My three OEM pumps have accumulated over 500,000 miles among them so no real complaints. Could happen at a more convenient location tho, than beside the highway in central Texas or on US-50 west of Vincennes, IN.

Each time one has failed I've managed to get back on the road without a tow, so that's good.

Hi George,
Sorry to hear of your fuel woes. Can only say "been there and done that". Last summer when I went east on my annual "migration" somewhere I was having major vapor lock problems in the heat. That was wile using an external fuel pump and regulator. I finally pulled over, unloaded everything and yanked the regulator. That seemed to have solved the immediate vapor lock until the return leg a couple weeks later while passing through Buffalo, NY when it reared its ugly head again. Off season I modified the aluminum bracket I made to allow more heat dissipation and isolating the pump body. That so far seems to have helped immensely but still, after resetting the floats that were way out of spec, I still have crap mileage.
I've been dealing with this crap for so long I'm about ready to pop on a new fuel pump. Looking for an easy way to check the pressures of the two pumps I have aboard. Not sure if the floats are out again or maybe the needles are trash...
You finding anything worth sharing?

No new news, Larry. LipSTick is running fine with the in-line pump. Haven't taken another look at STick (she's been sitting for 2 months.) New Suzuki is in the shop awaiting serious farkling, she'll get my attention for now.

So, I was having problems with my fuel pump (I thought) and I replaced it with the aftermarket (when I would do 70+ for a while it would end up dying. If I cycled the key it would activate the fuel pump several times and then run great, for a while.) After I replaced it I moved and life happened, I managed to take it out a time or two and everything was fine. I drove it on my way to my new job and it died on me a mile away from my house and I couldn't get it restarted. I am just now getting back to it now (almost a year later) I am thinking about just buying a new Honda brand one just to make it work...I'm tired of it not working. Any ideas or links to buy one the cheapest???

Ben

You might be seeing a issue with the fuel regulator. You can take it apart & look for a torn diaphragm to
be sure.....

Sounds like a plan, not sure where that is, so I will start a search.

I can't seem to find anything on a Fuel Regulator for a 1999 ST1100. Could you point me to a link? Or does only the ST1300 EFI use it?

Ben

Think of servicing the air cleaner. Take off the seat, bags side panels & air cleaner cover. The fuel reg is on the right hand side of the bike attached to the
air cleaner housing. Honda calls this a fuel shutoff or something close. The unit is above the fuel filter. Take off the 2 screws that holds the unit to the
air filter housing. Now remove the 4 screws the hold the assembly together. The diaphragm is meat of the sandwich. There is a spring to look out for as well.
The diaphragm has some steel in it but in mostly a thin elastic material something like rubber. The unit purpose is to shut off fuel flow to the carbs when the engine is not running.
The spring is to push the steel parts of the diaphragm into the seat area on the far side of the housing.
You might notice some tears in the unit. If you do, this is more than likely your problem. Several people have found this & there bikes run fine. My shut down
on 6 different rides & after this has been replaced with a blanking plate not one issues. This is rather long, MY BAD. Feel free to PM me if you have other questions.

The shut off can be bypassed too. When it is not torn it will keep gas from filling the engine when it id on it's side. I figured that if the bike were on it's side long enough to fill the cylinders,,,I had bigger issues to deal with. The bank angle sensor will kill the engine so that is still in tack to shut things down.

https://www.st-owners.com/forums/showthread.php?65298-ST1100-which-kind-of-vacuum-valve-do-you-have
In post #20 there are instructions to do the bypass. I looked for pics but could not find it.

Thank you guys so much for replying, I subscribed to the thread with an instant email, but it's not working so I just found the replies.

I did bypass the shutoff valve when I changed out the fuel pump, just for good measure, but that doesn't seem to have helped any. I just hooked it back up when I started working on it again, and I am still having the problem. I will open it up and check for a tear.

Ben

I've been running a couple of my ST1100s for years without the cutoff. As was said, it's just in case you fall over. Removing it just permanently removes a point of future failure. ;-) And if the ST falls over, you've got bigger problems than a little gas running on the ground ...

I was able to take the cutoff apart, and the diaphragm is indeed broken. I have bypassed it now, but should I plug the other tube (1/4") or leave it connected (but the fuel lines wouldn't be) or should I leave it disconnected from the cutoff, but open and hanging. By the way, it still doesn't run with a hoot with it bypassed. I think there is something wrong with my airtex pump...

You've got to plug the vacuum line that goes to the cutoff or it will not run worth hoot. ;-)

A quick plug, to verify the problem is the vac. hose, is to use one of the screws that holds the valve on the air cleaner case. It worked for me for many miles.

here is a picture of the pressure regulator in a st1100. it's in the plastic cap on top or the fuel pump. I opened it up, removed the check valve (takes some pressure for the fuel to over come) and tapped the inlet,1/8 pipe. Screwed in a 90 deg fitting then put it in line in the tank with a airtec fuel pump. I'm not sure how the fuel pump would last if it was pumping out all that pressure and the bike is at idle or long down hill with very little fuel needed. The vent hose is cut a little shorter but all in all 600 miles and no problems. Last pic is the finished product.. airtec pumps are $28 on ebay