1997 Evinrude 4hp tuning help

[matt167]

I have this 1997 Evinrude 4hp which I got cheap because it was lightly stuck and the carb was broken. It's one with an onboard tank AND a fuel connector. I got it freed up very easy, and then got it to run, but the broken carb needed fixed. The plastic choke cam was broken and all the linkage snapped.. The parts were about $60, but for the same price I bought a rebuilt carb from an '86 4hp which was only slightly different.. The difference is that on the original carb, there is a port for a crankcase vent and on the new older carb there is not. I plugged the crankcase vent and it idles. Took me a while to figure that one out.

I can get this thing to slow troll for a long time ( in the bucket ), but it seems like it looses fuel prime.. If I put fuel in the onboard tank, it seems to run fine, but it also seems to run off of the tank hooked to the fuel connector, just looses prime.. Without the crankcase vent, is there not enough pressure to use the fuel connector? I'm hoping to hang this on the back of my 14' Starcraft Holiday for lake trolling

 

[Crosbyman]

please post engine model ...several listed yours may have a transfer switch for the fuel
diagrams show a "pulse line" on some models but does not show where it goes ??

if you pump the bulb will it keep running ?

if yes ==> check fuel pump ,
check the screen filter under the cap
check for air leaks on the fuel connector..... if it sqwirts fuel when pumping

if you raise the tank above or in line with the engine does it run better ?
if yes==> weak fuel pump.... tank to low to suck gas from it in your test set up

make certain the tank vent is open ...or try to run with the tank cap off the tank
if ok===> tank venting faulty ...small vent hole crudded shut

 

[racerone]

The pulse hose may go to a fitting on the carburetor.-----That fitting may hide a little bladder ( used to be red years ago ) and that bladder might be called a fuel pumping element !

 

[Crosbyman]

yep.... 2 nipple carbs any documentation available ?? what improvement did this extra pulse line on the carb bring (presumably to improve things as always.... yet carbs ran 30 - 40 years with out it !

thanks

 

[matt167]

I'll have to get pics and model number tonight. The original carb did have a red bladder. I had to re use one fitting from the original carb to hook it up.

Is it just safe to run it on the top/ internal tank? I know it's just cobbled togther with the wrong carb but it runs mint as long as it stays running.. I did not put a lot of fuel in the internal tank which might be why it was giving fits. It did burn the fuel in the internal tank

 

[Crosbyman]

I'll have to get pics and model number tonight. The original carb did have a red bladder. I had to re use one fitting from the original carb to hook it up.

Is it just safe to run it on the top/ internal tank? I know it's just cobbled togther with the wrong carb but it runs mint as long as it stays running.. I did not put a lot of fuel in the internal tank which might be why it was giving fits. It did burn the fuel in the internal tank

which tank exactly is faulty ....you quote INTERNAL twice ?? or am I rerading this wrong

 

[matt167]

It turns out, I figured it out... It will run 100% perfect on the internal tank. It will not run well on the portable tank/ fuel connector. I filled the internal tank, and ran at a low idle for about 1hr after fiddling with the low speed mix just a little. I have a video I'm going to try to upload.

Next is to figure out how to fit the plastics back togther with the new carb. The plastics don't seem to line up 100%... But this engine cost me $80 at this point, for a perfect running 4hp. I just can only use the internal tank

 

[Crosbyman]

so what is wrong with the external tank... if it can run ok from a gravity feed
the problem stems from the pump's ability to bring the fuel to the carb

have tried raising the tank above the motor asa test ?
have you check the fuel filter in the pump cap ?
have you tried hand pumping the fuel and look for sqwirting gas... indicative of an air leak

I have no docs on the motor... does it have transfer valve somewhere ??

there must be a Y split on the fuel source

 

[matt167]

so what is wrong with the external tank... if it can run ok from a gravity feed
the problem stems from the pump's ability to bring the fuel to the carb

have tried raising the tank above the motor asa test ?
have you check the fuel filter in the pump cap ?
have you tried hand pumping the fuel and look for sqwirting gas... indicative of an air leak

I have no docs on the motor... does it have transfer valve somewhere ??

there must be a Y split on the fuel source

Yes, after it starts to falter on the fuel connector, I get about 1/4- 1/2 squeeze before it tightens up, but it does not seem to give it any extra fuel. I did not try the tank higher up as I did not hook up the portable tank tonight. I didn't check the pump either, but I have another complete pump here somewhere.. The only valve is the fuel shutoff which is activated by twisting the choke knob. Pretty sure the internal tank runs through the pump as well..
It's an E4REUC

​

 

[racerone]

The bulb does NOT stay rock hard once motor is running.-----1/2 squeeze when running is very normal.

 

[Crosbyman]

your carb has 3 nipples entering the carb... I presume one hose from the integral tank and... one from the fuel pump outlet pumping gas from the ..external tank ? and one hooked up to the pulse line ??

is this the set up ?

there seems to be a rotating valve to select one of two gas sources ?? if that is the case and the engine fails on the external tank you need to find out if external tank fuel flows into te carb when the valve is rotated

sorry all theory here ... no books to read up

 

[matt167]

your carb has 3 nipples entering the carb... I presume one hose from the integral tank and... one from the fuel pump outlet pumping gas from the ..external tank ? and one hooked up to the pulse line ??

is this the set up ?

there seems to be a rotating valve to select one of two gas sources ?? if that is the case and the engine fails on the external tank you need to find out if external tank fuel flows into te carb when the valve is rotated

sorry all theory here ... no books to read up

The carb that is on there now ( '86 4hp carb ) has 2 nipples but is otherwise the same as the original. The third small nipple went to a pulse line from the crankcase. I plugged that line and the engine runs fine.

The rotating valve is just a gas shutoff, according to the diagram on the plastic. But you pull that knob out for choke as well

 

[Crosbyman]

ok is it your wish to use just the top fuel tank (integral) because I do not think the external tank issue is resolved ?

your call

 

[matt167]

I would like both options to work, but I'm starting to think the carb will prevent the portable from working. As long as the internal works I can go fishing.

 

[matt167]

 

[oldboat1]

Add water -- about half way up the shaft would do.

 

[Crosbyman]

I would like both options to work, but I'm starting to think the carb will prevent the portable from working. As long as the internal works I can go fishing.

if fuel reaches the carb it will work but you have to figure the fuel flow from tank to pump and pump to carb inlet

 

[oldboat1]

32 is a fuel pump bladder, so 9 is (presumably) the nipple for fuel from an external tank. 42 is the choke knob. 29 is a fuel shut off -- guessing if it partially pulls out as suggested, that would be the directional valve between tanks (integral and external). Need to find a '97 oem service manual (try Ebay).

 

[matt167]

32 is a fuel pump bladder, so 9 is (presumably) the nipple for fuel from an external tank. 42 is the choke knob. 29 is a fuel shut off -- guessing if it partially pulls out as suggested, that would be the directional valve between tanks (integral and external). Need to find a '97 oem service manual (try Ebay).

I have the manual for a 1994 which is a very similar motor, but I have to locate it again. However the knob is marked on and off. The way the hoses are routed, which are as original except the pulse line which is plugged seem to suggest it is an on/ off