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Author Topic:   one last post before I call mechanic
johnnywhaler posted 08-06-2002 02:07 PM ET (US)   Profile for johnnywhaler   Send Email to johnnywhaler  
Boat runs fine at low speed, as soon as I give it some gas, it starts loosing rpm's and power. This problem occurred shortly after I got gas. At dockside boat rev's just fine.
gnr posted 08-06-2002 02:21 PM ET (US)     Profile for gnr  Send Email to gnr     
I had a similiar experience last weekend. My new to me outboard would start just fine but would sputter and die when I tried to give her some juice. Turned out the gas line was being pinched between the two 12 gal tanks under the seat.

It was a little embarrassing as almost everyone at the launch had a comment about my boat and then I couldn't get the darn thing running.

Hopefully your problem will be this simple.

Taylor posted 08-06-2002 02:22 PM ET (US)     Profile for Taylor  Send Email to Taylor     
I'm just guessing (since I'm pretty new to outboads) but could you have taken on some sediment laden gas or stired up something at the bottom of the tank and clogged a fuel filter or pickup? It takes a lot more gas to run fast than slow and not much to idle. You could be getting just a little through the filter. That's what I'd check first.
Tom W Clark posted 08-06-2002 02:28 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
It sounds like it's not getting gas. Many things could cause this. Check that the vent on your fuel tank is open and the hose in well connected and not kinked or pinched in any way.

Is the primer bulb collapsing or getting soft when this happens?

What boat, motor and fuel tank arrangment are we talking about here?

johnnywhaler posted 08-06-2002 02:54 PM ET (US)     Profile for johnnywhaler  Send Email to johnnywhaler     
Tom,(by the way it is an honor to have you answer my post)..It is a 93 100 hp Johnson far as gas tank ventalation goes it is a 28 gallon fiberglass tank (dont know what brand)the only ventilation I know of is that the gas cap is ventalated.? There is hole for a vetalation tube, but it is closed with a screw/bolt. Have had boat for three weeks and everything has been fine untill now, this was the third time i filled her up. Beggining to see value of four stroke....Johnny.
Tom W Clark posted 08-06-2002 03:07 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     

You should hope that Bigshot or Clark Roberts "honors" you with a response. The are the outboard guys here, not me.

That Johnson 100 hp you have is one of the best outboard motors ever built. Don't sell it short.

The gas cap vent is what I was thinking of. Are you sure the screw on top of it is open.

Two things to check the next time your motor dies:

1) Unscrew the gas tank cap and see if there is a sudden in-rush of air (this would indicate the vent is not working properly)

2) Squeeze the primer bulb until it gets firm and see if the motor then runs fine. This will indicate you have a fuel restriction somewhere be it from a hose/vent problem or fuel filter problem.

Do you have a fuel filter/separator installed? I believe there is also a small in-line filter under the engine cowl you might want to check too.

johnnywhaler posted 08-06-2002 03:26 PM ET (US)     Profile for johnnywhaler  Send Email to johnnywhaler     
Thanks Tom, I did get you (Tom Clark) mixed up with Clark Roberts, but it was still an the way when would one asume that it's a fuel filter, if that needs to be replaced what would the engine act like?
Bigshot posted 08-06-2002 03:48 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Did'nt I answer this question already? If not it will be the 2nd 100hp with bad fuel on this forum.

If you have a seperator....change it. Pull cowl and squeeze ball and see if you get gas squirting anywhere. If so correct and trial. Could be a bad fuel pump diaphram so check that. It is where your fuel line goes into a box. Take that box apart and inspect the rubber diaphram for a pinhole or other. Do as Tom told you and if you get some power, try squeezing bulb while somebody drives. Make sure you do not fly out of the boat when it kicks in. If no dice on bulb(still hard) try squirting some gas in the carb and see if it bogs or picks up. If it bogs, not fuel related, try new spark plugs. Could also be lower unit is tight but HIGHLY doubtful. Start with filters and connections and report back. An engine will run great on 3 cylinders at the dock but will not plane or barely plane, etc. I am betting on fuel. If no idle then I would say clean carbs buit this is opposite so it has to be something obvious. Something as stupid as pickup screen on fuel line could be clogged but it would still git for a minute or two.

Bigshot posted 08-06-2002 03:52 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Please do not post the same thing in 24 hours. I hate double posting.

have you tried anything yet? Do you have a separator?

johnnywhaler posted 08-06-2002 04:15 PM ET (US)     Profile for johnnywhaler  Send Email to johnnywhaler     
Sorry for the double post Big, last thing I want to do is piss you off. Yes it does have fuel separator/filter, and as soon as I figure how to get it off will examine. the guy who owned the boat before me either bolted or glued the oil tank right next to the fuel filter and it's in my way.
johnnywhaler posted 08-06-2002 04:58 PM ET (US)     Profile for johnnywhaler  Send Email to johnnywhaler     
OK guys, took the boat out again, ran fine for a few minutes, then motor konks out, check the bulb, feels empty, squeeze it, motor starts back up, had to go to back of boat every ten seconds and squeeze to get back to my dock. Will reread previous posts to see where i stand, appreciate everbodys' help...johnny
whitefoot posted 08-06-2002 05:49 PM ET (US)     Profile for whitefoot  Send Email to whitefoot     
something similar happened to me last summer and it was caused by my fuel tank vent being clogged. This caused a vaccuum in the fuel line. Only happened when I got on it...and my motor is a Johnson 100 GT...a '94 though. I think they redesigned the '94 and produced a completely inferior least that's what my mechanic told me.
johnnywhaler posted 08-06-2002 06:02 PM ET (US)     Profile for johnnywhaler  Send Email to johnnywhaler     
Thanks, I'm going to assume it's a fuel filter and change it first chance I get.The hoses seem fine, no crimping anyhere I can see (I suppose they can have a pin hole or something in them) I think my gas tank is venting (no rush of air) when i open it. One thing I dont understand though is how it is venting, no vent hose, no screw on top of cap, i'm assuming the cap goes on just loose enough to vent since everything has been fine up to now and the previous owner had no problems.
Clark Roberts posted 08-06-2002 06:19 PM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
Johnny, suggest you get a clean portable tank complete with hose, bulb, connector etc and put fresh 89 octain and run it! If problems go away then attack the fuel sys,,, clean/replace ALL! Happy Whalin' .. Clark.. SCN
Salmon Tub posted 08-06-2002 06:26 PM ET (US)     Profile for Salmon Tub  Send Email to Salmon Tub     
If you had to go and prime the bulb and this solved the problem, at least for a short span, then, I would assume the problem is prior to bulb. You may have blockage in the fuel line, or in the pick-up in the tank. What kind of tank is it? I assume that with a 100 hp (94), you must have a Montauk? If the tank is external, then do the following. Pull your fuel line out of the bilge and set the tank on the RPS. Remove the fuel fitting that connects line to engine. Take a gas can, preferably at least 5 gallons, place the gas can lower than the tank (on ground if fuel line is long enough) and put the end of the fuel line (engine side) in the can and give the primer bulb a few sqeezes. It should start to siphon the gas into the can, and the flow should be good, meaning the whole diameter of the fuel line and solid, no trickling, sputtering, or air bubbles. Empty a good 5 gallons or so into the can. If there is nothing wrong with either the fuel line or the tank and cap, you should have no decrease in flow for the whole duration. If there is a gradual decrease, pull off the tank cap and see if it corrects.

It may also be the fuel fitting that connects the tank to you engine.

bsmotril posted 08-06-2002 09:38 PM ET (US)     Profile for bsmotril  Send Email to bsmotril     
If it runs sqeezing the bulb, but dies otherwise, could be a perforated fuel pump diaphragm. Easy and cheap to change out.


johnnywhaler posted 08-06-2002 10:15 PM ET (US)     Profile for johnnywhaler  Send Email to johnnywhaler     
Fuel pump diaphram? Bigshot says it is were the fuel line goes into a box. What box? Where is this box?
Bigshot posted 08-07-2002 09:58 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Follow fuel line into the engine. You will see where it first goes into a pump or box type thing. From there it will go to carb. Trace all lines and make sure none are leaking gas first. An airleak will make the hose lose pressure.
johnnywhaler posted 08-07-2002 10:51 AM ET (US)     Profile for johnnywhaler  Send Email to johnnywhaler     
Hate to keep bothering you guys..But... when I change the fuel filter is there something I'm supposed to turn off? Started to unscrew the old one and a lot of gas started to pour out, screwed it back in for now untill I recieve further instructions.
Bigshot posted 08-07-2002 01:45 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     

Just unscrew. If you want, crimp the line with visegrips but I doubt much more will come out. Make sure bulb is hard after new filter is installed or it will take a while to prime that filter with gas. You can also pre-fill it.

johnnywhaler posted 08-07-2002 03:53 PM ET (US)     Profile for johnnywhaler  Send Email to johnnywhaler     
New filter installed, engine still fials, ball still gets soft. will try searing for fuel pump diaphram, is there a possiblity the fule pump itself is shot?
gnr posted 08-07-2002 04:07 PM ET (US)     Profile for gnr  Send Email to gnr     
Follow Clark's advice and try a portable tank et al. This will tell you if your problems are in the motor or in the fuel supply system. The first rule of troubleshooting is... Try the easy stuff first.
johnnywhaler posted 08-07-2002 05:59 PM ET (US)     Profile for johnnywhaler  Send Email to johnnywhaler     
Got portable tank, engine still dies out, so now I guess it's the fuel pump, there is one filter that i can see connected to the gas line.
johnnywhaler posted 08-07-2002 06:39 PM ET (US)     Profile for johnnywhaler  Send Email to johnnywhaler     
the fuel pump (if thats what im looking at) seems a little complicated to me, does anybody know what these things cost before I start taking one apart...?
Taylor posted 08-07-2002 08:21 PM ET (US)     Profile for Taylor  Send Email to Taylor     
Hmmm... I was really betting on the supply side of the equation. But if the bulb gets soft, but does not collapse that indicates to me that the problem is closer to the engine.

So three things closer to the engine on my boat - the big external water seperator/filter, an inline filter, and the pump.

I know how you feel about the pump. My confidence (and ability) begin to fade at that point.

Do you have, and did you change the inline fuel filter?

johnnywhaler posted 08-07-2002 10:33 PM ET (US)     Profile for johnnywhaler  Send Email to johnnywhaler     
Taylor,I have not yet changed the inline filter. Are these standard? Can I get them at Marine West, or do I have to get them from dealer?
Bigshot posted 08-08-2002 09:44 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Ok this is getting long in the tooth guys! If you honestly can't change a filter.....take it to a mechanic. The diaphram IS the fuel pump. DID you try pumping the bulb while it was "failing" like we told you? Did it correct the problem?
johnnywhaler posted 08-08-2002 01:09 PM ET (US)     Profile for johnnywhaler  Send Email to johnnywhaler     
Yes Big, if I squeeze the ball it stays running both on the boat tank and portable tank that i got, dont see gas comming out of any of the lines, supose it could be the inline filter but I'm thinking fuel pump, I spoke to a mechanic that could come out in a day (most of them say 2 weeks) and he recommends that I replace pump (wich I can buy down street)so I dont think he is trying to charge extra for that since i will by it myself. He says he allways has problems when he just changes the diaphram and gaskets, I called Johnson and they say just get a kit, but the mechanic says he doesntly want to use kit because he doesnt want to guarntee his work if it stops working again. I probaly can find mechanic that will recommend just fixing pump, instead of replacing it, but that is going to take time, I could try doining it myself but as Clint Eastwood once said "A man has to know his limitations" so I will make decision shortly and stop bothering you guys. I appreaciate your help...
Bigshot posted 08-08-2002 01:36 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Very we are getting somewhere. that is the info I was seeking. Now go out there and buy the pump. Then disconnect the incoming and outgoing lines and replace pump. Will take you 15 minutes. Gotta test your limitations also.
bsmotril posted 08-08-2002 04:15 PM ET (US)     Profile for bsmotril  Send Email to bsmotril     
An outboard fuel pump on a carb'd engine is pretty simple and easy to replace. It is basically a rubber diaghram that moves in and out. It covers two chambers cast into the block. On chamber feeds crankcase pressure pulses to the diaphragm making it move. The other chamber contains the fuel being pumped. It has checkvalves on the inlet and outlet preventing backflow. What breaks over time is the diaphragm.

Trace the incoming fuel line into the motor cowl, through the likely inline filter inside the cowl, to the point where it terminates on the engine block. This will be on or near a removable plate/cover held on with anywhere from 2-4 screws. Ther is also the outlet fuel hose attached to this same area that will go the the carb(s). Remove the screws and you'll see the rubber diaphragm. Remove the old one, insert the new one, clean the mating surfaces on the block and cover, then reinstall. Torque to proper tightness so as not to cut into the rubber diaphragm.

scarlson posted 08-08-2002 04:44 PM ET (US)     Profile for scarlson    

Check the O-rings on the female connectors on both ends on the fuel line. On my buddys 13" BW we had the same problem. On his it was just a mater of putting on a new fuel line assembly once we had the new connection on the problem went away. At higher speeds air was sucked in and displaced the heavier gasoline. It doesn't take much of a gap. It's a cheap fix if it works.

johnnywhaler posted 08-11-2002 10:42 AM ET (US)     Profile for johnnywhaler  Send Email to johnnywhaler     
Well finally changed the fuel pump, after I got a few warnings from mechanic and part supplier about dangers of trying to fix the fuel/oil pump myself. Anyway boat now runs, thanks for all your help. Fuel pump cost=240 dollars, big bottle of asprin= 8 dollars.
Taylor posted 08-12-2002 01:32 PM ET (US)     Profile for Taylor  Send Email to Taylor     
Satifaction gained from fixing it yourself = priceless.

Geeze, were the heck is Bigshot when I need him? ;)

Good work, johnywhaler. The reliabily of a boat is the combination of the equipment and the operator, and your boat just became more reliable.

triblet posted 08-12-2002 11:19 PM ET (US)     Profile for triblet  Send Email to triblet     
And the operator gained knowledge which will
also help keep the boat reliable.


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