Ford Lehman sp135 automatically goes to idle from 2k rpm

[CharlieO.]

We used to grease the threads on the fill caps to help prevent water intrusion.

You may also want to consider adding some type of biocide before you start accumulating organisms due to water in your tank(s).

 

[grandbanksbayfield]

If you used 30 Racors, a lot of gunk may have gotten through to your secondary filters on the engine. You must then change the engine filters (2-4) microns before you can be sure it is not a filter problem. Am. Diesel recommended that i switch from 30 to the blue (16 I believe) filters on the Racor after this happened to me. That way, you might not have to chaange the secondaries on the engine - a tricky job. For now, filter changes is much simpler than messing with fuel lines.

 

[paulga]

If you used 30 Racors, a lot of gunk may have gotten through to your secondary filters on the engine. You must then change the engine filters (2-4) microns before you can be sure it is not a filter problem. Am. Diesel recommended that i switch from 30 to the blue (16 I believe) filters on the Racor after this happened to me. That way, you might not have to chaange the secondaries on the engine - a tricky job. For now, filter changes is much simpler than messing with fuel lines.

that could probably be what have clogged the spin-on filters. for some reason the previous owner was using 30mi racor filters so I picked 30, also fearing 10mi could clog more quickly. at that time we suspect it was the bad fuel that we got at one marina along the way.

I'm thinking next thing is to pump the water out of the tank, add biocide additives and swtich to 10mi racor filters as there are multiple spares onboard

 

[High Wire]

A mechanic changed the spin on filters, the engine has been running well. We just arrived at Jersey City.

The mechanic found water in the bowl of one spin on filter. Could rain water get into the tank through the fuel fill cap?

YES! One of several ways into your tank. Check the oring on the fill caps. Your racor should have caught it. Have you tried draining water from BOTH Racors? Wouldn’t be the first to be checking the wrong racor.

 

[catalinajack]

I would guess fuel restriction somewhere. Check both fuel filters. You can visually see the condition of the Racors but the spin on cartridges filters are tough to evaluate. Do you know the Micron size of the filters? They might be 2, 10 or 30 Micron. 30 Micron has the largest holes. Sometimes too fine a filter will restrict flow after a while.
Your fuel delivery system has two parts. Suction from the tank and then pressure to the injectors. A hole/ leak in the suction side will draw in air bubbles causing this kind of issue. Are you Racor bowls full of fuel to the top?

TJM, you are mistaken about fuel flow through different micron sizes. ALL Racor filters in a series have the SAME flow rating, but, yes, a 2-micron filter will stop flowing fuel more quickly. OP, a vacuum gauge mounted on your Racor housing will tell you when the filter needs to be changed.

 

[catalinajack]

You say racors. Usually, the racor is used as a primary filter before the lift pump. A filter after the lift pump might be a spin on, or draw stud type. This is the secondary filter. Usually a finer media than the racor primary.

Of course someone may have installed a custom setup, we have no way to ascertain without pictures.

If you changed both the primary and secondary filters, the next thing old be the rubber hoses, followed by the lift pump.

If the lift pump isn’t working, you can temporarily install an electric in series to get you home.

Why a temporary installation? A Walbro electric pump is rated for 18,000 hours.

 

[catalinajack]

You are missing something. Your Racor set up is nice, dual filters are useful. Currently the valve is turned so the fuel is flowing thru filter #1 ONLY. When and if that element gets clogged you can switch to filter #2 by rotating that silver valve in the center clockwise 90°.

Those pressure gages are NO good for low flow engines like the FL135. They will always show in the green. Plus unless they were modified they DO NOT FIT the Racor 500 series. The thread in the center is too long and bottoms out before sealing the top. I have had extensive conversations with Racor on this. I have the FL 120's.

There are 2 other spin on cartridge filters after your Racor. Have you checked them?

That is interesting about the gauges on Racors. I had a pair of FL120s. Instead of Racors, I installed Tony Athens sequential filter heads with his vacuum gauges. Yup, the gauges showed progressive increases in the green as indicated by the drag needles. I have no explanation as to why mine worked and the Racor product does not.

 

[Choices]

My Raycor gauges work perfect. I can not imagine not having them on a single screw.

 

[Bmarler]

Why a temporary installation? A Walbro electric pump is rated for 18,000 hours.

I’ve got zero issue going electric for the lift pump. Some people prefer to stay original though.
Good point though, nothing wrong with a good quality electric pump. Just make sure it delivers the right flow at the right pressure.

 

[TJM]

Catalinajack: To clarify, my statement was "sometimes too fine a filter will restrict flow" IF it gets clogged with particles. I thought it in my head but did not type it exactly.

A 2 micron filter is more likely to get clogged over a 30 micron filter. Our older FL120 engines, 1982 vintage run fine with 10 micron filters. They are very hearty and have a very low flow rate compared to the higher horsepower engines. I would much rather change a Racor than a spin on cartridge filter on the engine. The Racor does not need bleeding.

I just looked at the Racor site and it appears as though they have a new model that works with the 500 series engines - low flow. That is great, my info was from 2015 ish models where the center thread was too long and did not seal the face gasket.

 

[MaDehn]

Think about adding a fuel polishing system-- fuel pickup that goes to the bottom of the tank, electric fuel pump from an automotive shop (cheap) and a Racor filter then Tee that into the fuel return line from your engine. simple switch or have it run whenever you are running your engine- this filter will then immediately let you know if you have water in the tank as well as pulling small amounts out. Check to see if your fuel fill cap has a rubber O ring- most do and these deteriorate over time -- 50 cents to replace and this keeps water running down your deck from detouring into your fuel tank from a faulty seal. on the pickup tube for the polish system, cut the bottom of the tube at a slight angle so that it is just barely off the bottom of the tank. Another think to check is the pickup tube for your main engine- some of these have screens in them that can get clogged up and cause intermittent issues- if yours has such a screen, i would take it out- your racors are more than capable of providing filtering. best of luck--

 

[paulga]

Think about adding a fuel polishing system-- fuel pickup that goes to the bottom of the tank, electric fuel pump from an automotive shop (cheap) and a Racor filter then Tee that into the fuel return line from your engine. simple switch or have it run whenever you are running your engine- this filter will then immediately let you know if you have water in the tank as well as pulling small amounts out. Check to see if your fuel fill cap has a rubber O ring- most do and these deteriorate over time -- 50 cents to replace and this keeps water running down your deck from detouring into your fuel tank from a faulty seal. on the pickup tube for the polish system, cut the bottom of the tube at a slight angle so that it is just barely off the bottom of the tank. Another think to check is the pickup tube for your main engine- some of these have screens in them that can get clogged up and cause intermittent issues- if yours has such a screen, i would take it out- your racors are more than capable of providing filtering. best of luck--

what fuel polishing system would you use? I'm considering to add one as it will be handy to get the water and impurities out of the fuel before a trip or after a long time the fuel sits. But the installation requires connection b/t the engine and fuel tanks like you described, that's where the challenges are for me.

 

[Capn Bob]

yesterday we traveled 18 hours with no issues. today's trip started from 6am, we fueled up before noon, cruised at 2k rpm same as yesterday. temp, pressure, voltage have been within normal range. around 5pm the engine suddenly rolled back its rpm to idle. we returned the throttle and gear to neutral then throttled up, the rpm climbed again. soon after cruising at 2k, it throttled to idle again. since then we maintain the rpm near 1900 and still monitoring.

has any one with FL observed similar issue?

We had exactly the same issue with one of our SP135s while in the middle of Chesapeake Bay. It turned out to be a failing mechanical fuel pump with a somewhat porous diaphragm. The engine would run, but only at a low rpm. The other posts were correct in that the engine is very likely starved for fuel.

 

[C lectric]

Yes, water can bypass the fuel filler caps if the seals are in poor condition or have a poor fit
. Every few years I replace my O ring seals and every year I lightly grease the O rings. Just be sure you get the correct size O rings.
The caps should screw in with some LIGHT resistance hopefully ensuring there is NO water pathway remaining.

And use the cap tool to ensure it is tight in the housing. Hand, literally hand tightening will not be good enough.

 

[Comodave]

You actually don’t have spin on filters. Lehmans have CAV type secondary filters. The Racors aren’t spin on filters either. No way would I get underway with only 1 spare filter aboard. Filters are cheap so carry quite a few.

How do you check the spin on filters?
We have two spare spin on available