unexpected electric fan problem

[TX]

In my rebuilding of my 62 3B, I replaced the mechanical fan for an electric one, in an attempt to increase power, and gas mileage.  But I experienced a problem that I had not anticipated, while pulling  away from a stop sign.  While accelerating, I experienced hesitation which felt like fuel starvation.  I  pulled over and increased  pressure on the fuel regulator, which seemed to help, but not completely. Upon arriving home I noticed  bubbling in the fuel pump bowl while the engine was off.  Obvious signs of vapor lock. I measured the temp of the fuel line coming out of the pump @160F.  I  wrapped the exhaust with insulation as well as the gas line itself. That helped but bubbles still persists.  The pump itself measured 165F , the block temp was 199F. So, I installed  5 layers of gasket material to insulate between the pump, and block, which also helped. 
I was wondering if anyone else has problems with ethanol fuel, or is it because of my electric fan not running constantly, cooling the  engine compartment?

[aboyandhisdog]

I have seen many (maybe all) fuel pumps with the glass top "percolate" fuel as you have described, and I don't think that is a bit unusual.  That said, I do think putting as much insulation between the fuel lines and the exhaust manifold is a good idea.  I even re-routed my rubber fuel line well away form the exhaust.  The purists won't like it, but I no longer have issues with "hot fuel" or vapor lock, etc.  I'm sure that this effect is indeed exacerbated by ethanol in the fuel, but in my experience (with the L-head) ethanol has little, if any, negative effects to the running of the engine in my day-to-day driving.

Now when you say you added 5 layers of gasket between the pump and the block, do you mean that you added gaskets to the base of the pump?  If so, would that not decrease your fuel pressure?  I don't know that it would with the F-head, but with the L-head it moves the pump arm further from the lobe thereby reducing pressure.  I'm pretty sure I have this right.  Might be something to look into.

As for the effects of going to an electric fan, I have no experience with one, but if it is controlled by a thermostat I would think it would still be doing it's job to cool things down.  Sorry I can't be more help.  Good luck!

[SteveKfl]

I was considering the electric fan conversion, so I'm wondering, did you measure the temp before and after the therm housing and rad hose, and also the return rad hose temp to see radiator efficiency and/or if the thermostat may be too high, or not working properly to include the radiator as needed? 

[TX]

stevKfl - It worked perfectly.  Temp at the outlet pipe was max temp 180F, temp at the inlet pipe was 165F.   When you come to a stop, there is a time lag until the fan comes on (approx. 1 Min.). During this time, the  engine compartment gets a little hot.

aboyandhisdog- I removed the metal spacer under the fuel pump and replaced them with the stack of gaskets, so that the  pressure world not change.  The gasket insulator did reduce the fuel pump temp to 135F. This slowed the bubbling quite a bit.
On my 3A, I have observed normal peculation of fuel in the pump. But the engine was off, and there was bubbling coming from both the intake and exhaust ports.

[64CJ5]

I have an electric fan on my M38 with a Pinto engine.  It comes on when the engine starts, not controlled by a thermostat.  My compliant is that it is loud.

You might wire the fan to the run when the engine is on and see if that helps to cool the engine compartment.

[TX]

Good point. Wiring the fan to the ignition circuit would solve my vapor lock problem, but it would negate my attempt to save fuel when driving. When I realized  that a fan could draw as much as 20 hp from an engine output, I decided to install an electric fan that  turns off when not necessary. 
Excessive fan noise was my other consideration in installing a fan.  I  measured the mechanical fan on a 3a with the decibel meter on my phone, which may not be that accurate, but it would be consistent. It measured 82 dbl at idle while the 3b with electric fan measured 78 dbl,  both pretty comparable. Both are just a little louder then the engine. But I have noticed the mechanical fan is very noise at high RPM, say, climbing a steep hill in low gear. An electric fan runs at a constant speed, so its noise would be the same as at idle. 
Basically, I am pleased with the electric fan. It does not run until it gets up to running temp, and shuts off when driving. When stopping at lights, it is quiet until the engine heats up, which could take several minutes.
I think, I am going to install an electric fuel pump on the firewall, and reroute the fuel line away from the exhaust manifold.  I'll have to remove the mechanical altogether.  I hate to do it, but sometimes we must adapt to new conditions, like the availability of decent fuel.

[SteveKfl]

Would it be sensible to relocate the fan thermostat "setting lower" and/or "location" nearer to the 'fuel pump area' to sense temps needed to run longer?  IMO, The idea of the ignition and fan combined at "start up" is quite an Amp Load at first 'power up'.  Another option might be, a bi-pole 'toggle switch installed' and that would allow optional 'thermostat control' or 'manually control' the fan operation as desired.  Have temps been compared at the firewall where the electric fuel pump might be mounted 'trapped out of the air flow' of the engine compartment?  Does the CJ3B have fender well vents?  I don't remember.  With a Flat Hood even with 'fender well vents driver's side' by exhaust manifold, the #4 cylinder temps are a lot hotter than #1 temps, as something to consider.  A L-Head test by Colin P with a digital thermometer using a 180 degree thermostat at "operating temperature", showed a difference of almost +20 degrees at the #3/4 plug areas compared to the #1 where the fuel pump is mounted.  See attached pics.  Just some more options to consider.  Good Luck!   

[TX]

These are great  thoughts that I had not considered. The engine is designed to operate at 180F.  The fan switch is designed  to switch on at 180 F, and turn off at 165F. . Relocating the therm o switch closer to the pump would not help the pump to stay cooler since it is programmed to turn on at 180F, well above the boiling point of alcohol 165F.  Having a manual switch complicated the  driving of the vehicle. I would like to keep it as simple as possible.  Yes, there are fender vents on a 3B.
The engine wall  beside the pump is 199F, and the exhaust is 356F. Rerouting the fuel line away from these  hot areas seems the simplest and most elegant  solution so far. 

Since researching this problem, I have come to realize, I am not alone. Many older vehicles are experiencing the same problem.
I suggest other owners look into the possibility of vapor lock. They may  be experiencing a problem and not realizing it.
 

[SteveKfl]

Here's my solution to keeping the heat and noise in the exhaust pipe and away from everything else around it.  Racer's heat tape.  Please keep us updated.  Thanks.

[TX]

Very nice wrapping . Looks  neat and clean. My attempt is not so elegant.

[TX]

In my research, I discovered that in the 60s and 70s, manufacturers were confronted with of the vapor-lock problem, and relied on a vapor filter which separated the gasses from the liquid fuel. The vapor was then vented it back to the gas tank in a separate line.  Many  vintage car enthusiasts rely on this problem solver today.  Although it is still not a perfect solution.  It only vents gasses at the highest point, the carburetor.  I witnessed gasses at the fuel pump. The expansion of fuel at that point would increase pressure and push fuel into the carburetor and flood it.
Who's idea was it to dilute perfectly good gasoline with an almost inert substance like alcohol.  One year, I had to replace two fuel pumps in two separate jeeps. It had to be from the alcohol eating the seals. This was a common problem when ethanol was first introduced.