In-line fuel filter

jaybirddog11 · May 15, 2010

1979 100hp Chrysler. I recently added an in-line fuel filter. Now I am having issues with not getting enough fuel. It keeps bogging down and I have to have someone keep pumping the primer bulb. I have the vent open on the tank. I currently have a 5/16" fuel line. I am thinking of up-sizing to a 3/8" fuel line. Any suggestions or thoughts? My fuel pump diaphragm was replaced around 2.5 years ago. How long do they typically last?

Here is a pic of the filter I am using.

jerryjerry05 · May 18, 2010

Re: In-line fuel filter

The filter shouldn't make that big a difference.How old is the squeezie?
Ethanol is screwing up LOTS of motors and diaphrams.You need to check the entire system and replace any weak or old hoses.Replace the hose/squeezie from the tank.J

Frank Acampora · May 18, 2010

Re: In-line fuel filter

If you look at the filter disassembled, you will see that where it screws together there is a hole in the center shaft. If it screws too far the hole will be partially blocked and if the wrong filter element is inside it may block the hole almost completely. I needed to do a good bit of grinding on mine to ensure adequate fuel flow.

I suggest you use a cheaper 3 dollar plastic disposable filter. I actually use a six dollar 90 degree filter purolator #F50153 available in most auto stores.

I also suggest that you change the diaphragm--they do harden with age and lose some capacity. Again, if the only change you made was the filter, then logic tells us that the filter must be the culprit.

I thought that was a glass re-useable type but on closer inspection of the photo, I see it is a disposable. However, perhaps the paper element is too restrictive. The one I recommended has a fine plastic screen and I feed anything from 20 up to 140 with this filter--no fuel flow problems. Remember, if you put this filter between the pump and carbs, you have the option of removing the screen at the pump inlet cover.

moparman · May 18, 2010

Re: In-line fuel filter

also check to make sure it's flowing in the right direction,most filters will be marked with an arrow indicating the flow direction,it makes a big difference on the smaller boat fuel pump as to which way you have the flow going

jaybirddog11 · Jun 1, 2010

Re: In-line fuel filter

Frank, would you recommend using a fuel/water seperator filter?

davidjamesburton · Jun 2, 2010

Re: In-line fuel filter

I'm having fuel problems also.

Primer bulb collapses flat during engine running WOT but not at low revs. replaced fuel filters and put in new primer bulb. some crud in the old filters but not enough to really block membranes. ? problem with fuel filters as described by Frank (ie blockage immediately PRE-filter due to the central rod of the filter plus a bit of crud). Interestingly when i disconnect the fuel line post primer bulb and then squeeze the fuel out of the primer bulb the bulb takes about 30secs to reinflate! am assuming must be a partial blockage in the fuel line between the bulb and the fuel tank.

Any thoughts?

ENSIGN · Jun 2, 2010

Re: In-line fuel filter

The ethanol in todays fuel will destroy a primer bulb from the inside out.You're going to be better off removing that cheap filter and installing a fuel water separating filter between the primer bulb and the motor

Snoots · Jun 2, 2010

Re: In-line fuel filter

Is it ok to have both an in line screened filter and a water separating filter? If so, is there a particular order? Must the water separator be between the bulb and carbs?

foodfisher · Jun 2, 2010

Re: In-line fuel filter

Water seperator immediately after the tank and before the squeeze bulb. Inline filter just before the carbs.

further · Jun 2, 2010

Re: In-line fuel filter

As foodfisher said exactly. I just installed a fuel/water separating filter between the bulb and tank and a small plastic inline filter between the fuel pump and carbs on my 88 85hp and ran it for the first time last weekend and had no ill affects at all.

pnwboat · Jun 2, 2010

Re: In-line fuel filter

I've been running a fuel/water separator between the bulb and tank, and an in-line filter between the fuel pump and carbs now for about three years now. Have not had any problems with it.

davidjamesburton · Jun 3, 2010

Re: In-line fuel filter

Apologies to jaybirddog for dropping my question onto his thread. Am new to forums and didn't know the etiquette.
thanks to all responders
Dave

brianvolt7 · Jun 3, 2010

Re: In-line fuel filter

Frank Acampora,

You posted ?you have the option of removing the screen at the pump inlet cover?, will this have any side affects to the performance and it the screen the only type of stock filtration for the fuel system?

jason32038 · Jun 8, 2010

Re: In-line fuel filter

I would never use an inline paper fuel filter for a 2 cycle mixture. Remember this fuel has oil in it and the oil could possibly be clogging the filter itself and restricting a sufficient amount of oil from the engine. The engine has a screen filter to keep out debris and it's in the plastic housing. A water seperator can be added.

Frank Acampora · Jun 8, 2010

Re: In-line fuel filter

No performance effects at all. In fact, my opinion is that since the screen is before the fuel pump it is almost useless. I removed both from my twin pump 140. I have a water filter at the splashwell and an inline filter (Purolator F50153--6 bucks) between the pump and carbs.

jason32038 · Jun 8, 2010

Re: In-line fuel filter

jaybirddog11 said:
1979 100hp Chrysler. I recently added an in-line fuel filter. Now I am having issues with not getting enough fuel. It keeps bogging down and I have to have someone keep pumping the primer bulb. I have the vent open on the tank. I currently have a 5/16" fuel line. I am thinking of up-sizing to a 3/8" fuel line. Any suggestions or thoughts? My fuel pump diaphragm was replaced around 2.5 years ago. How long do they typically last?

Here is a pic of the filter I am using.

View attachment 53130

http://www.oreillyauto.com/site/c/d...word=universal+fuel+filter&pt=N1226&ppt=C0262 <<This is the only type of inline filter id use for a 2 cycle engine. I believe the filter element is made of neoprene or nylon not paper.

foodfisher · Jun 9, 2010

Re: In-line fuel filter

That's the one I use. Because it's glass, I wrapped it with a slotted piece of PVC to cushion it against breaking. The slot lets you see the fuel flow.

jaybirddog11 · Jun 22, 2010

Re: In-line fuel filter

Well, I have done numerous upgrades since the inline fuel filter issue. Here is what I think resolved the problem. I replaced the fuel pump diaphragm, check valves, used the fuel filter Frank A suggested, static timed the motor and cleaned the carbs. My timing was way off. I was having problems with cylinder #3 prior to retiming my motor. The spark plug was clean. I checked all head bolts for correct torque and was surprised to find that about half of them were loose. Took the boat out Sat. night and all four plugs look identical now. What a relief. However, when I had to go through the marina at the no wake zone, the primer bulb went flat again. I figured I would get out into open water to WOT to try and clear any debris in the carbs and bingo, fixed the problem. I know all of these issues needed to be fixed but I did a quicky carb cleaning instead of letting it soak overnight. I am now the happy owner of a properly functioning outboard!!!
Max RPM 5500, fully loaded boat and still went 30 mph,gps (4 BIG adults and too much gear, not enough beer) and this was without properly trimming the motor and balancing the weight in the boat. I bet I get close to 40 MPH next time out!! I hope this info can help someone out in the future.

foodfisher · Jun 22, 2010

Re: In-line fuel filter

Man-o-man, do I know that feeling.

In-line fuel filter

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