67 Dauntless 225 V6 Fuel Line Upgrade

To start off, I inherited a very modified jeep and it's been an ongoing project and thanks for the help getting it to a point where I can hit the desert for hours on end without major problems.

I'm finally at the point where I could address a very sloppy fuel line setup that's been bothering me and giving me an overall sketchy feeling when out in the desert.

When I got it:

1. Dual tank with one under the seat and one rusted out custom rear tank.
2. Dual tank switch.
3. All rubber fuel line.
4. Fuel pressure gauge.
5. Mechanical pump.
6. Electrical pump before mech pump.
7. Return on mech pump blocked.
8. One large clear filter just after tank switch.
9. One clear sight glass filter just before carb.
10. Carter AVS carb.
10. Vapor lock problems.
11. Low pressure.

Long story short, my mech pump went out so I when through some gyrations with makeshift fixes, weird pressure problems, fuel pressure regulator, no regulator, fuel filter location changes, ect. The last straw was after two days working great, fuel pressure went to zero without warning at the end of day 2. I decided to redo the whole thing and copy the stock setup the best I can and keep it stupid simple.

New setup.

1. One clean tank under seat.
2. One 5/16 hard line from tank to fuel pump.
3. One stock fuel filter just after fuel pump.
4. Hard line just after fuel filter running up to sender.
5. Rubber line just before pressure sender and very short hardline between sender and carb.
3. Return line added, drilled and tapped sender cover plate and added a length of hard line going to undercarriage.
4. Rubber fuel line going from pump to hard line for return.
5. Fuel pressure sender just before carb.

After a one hour test in the heat this weekend I had no vapor lock issues.

Question: Pressure is now fluctuating between 5 and 10 psi. I have no idea if this is normal. Pressure seems to climb when on the throttle but runs great otherwise.

Am I good to go finally? Thanks.

 

10 psi is too much

 

Yeah, you've got it all wrong.

The first thing you should be doing is ripping that Carter off and sending it to me. Once received, I MAY send you my Holley 390 for a minor set of adjustments, and you'll be fine.

Beyond that, I too would be wary of the 10 psi. The research I've done says 7 psi should be max, but that's for my Holley. Maybe the Carter runs higher? I think around 4-5 psi seems to be the desired pressure, unless you're running 600+ HP or something. I just picked up a Holley 4-7 psi electric for my 225 Dauntless and it seems to be fine. I've yet to seriously hit the road with it, nor the offroad. I did run it out for testing on a short highway run. Did fine.

My tiny Holley pump is rated at 32 gallons per hour (GPH) which means it would drain my fuel cell in about 30 minutes, which I pray it never will.

Others here have stated that without the return line on the mechanical pump, vapor lock is common. That's why it's there. No one has mentioned whether vapor lock is an issue with electric fuel pumps. Hopefully not--

So I'm a bit confused about how you're running now. Strictly mechanical pump, electric, or both? You started with both.

If you're running an e-pump, let me pass to you how both of mine have been setup, with the first being the EFI configuration that I'd installed while attempting to run throttle body fuel injection, per factory specifications.

Fuel tank >>>>>> 100 micron fuel filter >>>>> electric fuel pump >>>>> 10 micron fuel filter >>>>>> carb/EFI unit >>>>> return line to fuel tank .

This was with a high pressure 58 psi fuel pump for the EFI. The EFI had an internal regulator.

I then ripped out the EFI and opted to go with the low pressure electric fuel pump in place of the EFI high pressure pump, bypassing the mechanical pump.

The lower pressure Holley 10-433 4-7 psi pump comes with a mandatory 70 micron pre-pump fuel filter that screws directly to the e-pump.

Fuel tank >>>>>> 70 micron fuel filter >>>>>>> electric fuel pump >>>>>> 10 micron fuel filter >>>>>> Holley 390 carb >>>>> no return line (plugged)

The 10 micron post filter may not be necessary, but I left it on since it was already installed for the EFI.

If I was running the mechanical pump, I'd stick with a pre-pump filter of some type, then the fuel pump, then a post filter, then the carb. My motor came to me with that setup, however there was no pre-filter to the mechanical pump. Not sure if it needs one, but likely a good precaution.

Not to confuse you, but after removing my EFI and while waiting for my low pressure e-fuel pump, I ran it this way:

Fuel tank >>>>> 100 micron filter >>>>> 10 micron filter >>>>> mechanical fuel pump >>>>>> carb >>>>> return line from mechanical fuel pump to tank.

I'd just dropped the EFI fuel lines down to the mechanical pump so I could test it all and use it for a backup should my e-pump ever fail away from home. Note that there was no filter after the mechanical pump, but only to keep it simple for testing.

What you've described is a little confusing to me. Not sure if you could type it out like I've done above, but maybe you could draw it on paper, shoot a photo of the diagram, and post it here?

FYI I'm running all high-pressure rubber line, the 3/8" that came with my EFI system. They're not a fan of hard aluminum fuel line of any kind. 3/8" is fine pre-mechanical pump, but not post to the carb, nor for return.

 

I tried to summarize so if it's not in list 2, I dropped it. I like the way you summarized it.

Here it is:

Feed to engine:
Fuel tank >>> hardline >>> hose (5 inches) >>> fuel pump >>> hose (3 inches) >>> Filter >>> hose (3 inches) >>> hardline (up and over engine in front of air cleaner) >>> hose (8 inches) >>> hardline (4 inches) >>> fuel pressure sender >>> hardline (2 inches) >>> carb.

* all hose and hardline @5/16 for feed circuit
* stock replacement fuel filter

Return:
Fuel pump >>> hose (5 feet) >>> hardline >>> tank

* all hose and hardline @1/4 for return circuit

I'm not sure how to drop the pressure other than by using a pressure regulator. I'm not sure why the stock pump isn't regulating it.

Thanks.

 

Perfect.

I'm not sure whether a stock fuel pump will normally surge to 10 lbs. or not, and that no one has just ever noticed? I've never checked one. What about the gauge itself? I'd also wonder if you're using a stock fuel pump or aftermarket, and if aftermarket, was it Chinese? It might just be pumping wrong. I have more faith in quality electric fuel pumps than mechanical, for consistency reasons alone, though it may be moot. Mechanical pumps seem to work fine.

I'm a bit concerned as to whether my 3-7 psi e-fuel pump will overpower my floats, but I think not. Time will tell.

A lot of guys use fuel regulators with their systems, but some have commented to be sure to use a quality regulator because the 'cheap ones' fail quickly.

That's why I went with the Holley e-pump, for consistency and independence from the motor itself. I figure if it works for high-dollar EFI systems, it should work here as well. I installed mine with an independent shut-off switch. Also works as a great theft deterrent. If you don't switch it on, no fuel to the motor. It is also unmarked on my panel so it won't be easily discovered by a potential thief. That also gives me the ability to shut the fuel off while the key is still on, such as if stalling on a steep uphill climb with floats flooding the motor. I can shut the fuel off and use the starter to crank the Jeep in gear to get it out of trouble.

Besides the high pressure reading, are you experiencing any odd things out of the motor, such as surging or flooding? Might be an issue in your fuel pump itself. It would make sense that the fuel pressure might pulse higher when you're on the gas, because it's pumping faster before catching up. Some of the other guys might know better than I. If the floats aren't flooding I'm not sure it's a problem. Might just be your gauge.

BTW, I'm a former Kern guy myself. BAK from '80-'99. That's where I started wheeling. So many great areas to play around there, at least before I moved up north. Raced motocross there as well. Loved heading over the hill to the Red Rock area.

 

I'ld run it a while and check plugs. Does it climb with rpm or load?

 

Thanks 69CJ. I'm thinking the pump is not great quality but at least I've simplified things to where I can isolate the problem. I haven't experienced anything weird with the new setup but we'll see.

So it will run rich if there's excessive pressure? Yes psi does increase with with rpm.

Yes, It's pretty amazing here (if you're into off-road and outdoors). I'm at the north end of El Pasos and have some great mx routes depending on season. Have to be careful, it's pretty vast. I'm kinda screwed/dumb because I don't have anyone willing to ride so I'm usually solo.

 

I often rode solo locally, but we had a vast racing community so we'd meetup locally and turn everything we did into a race or similar. LOL. Lots of hill climbing, making impromptu race tracks everywhere, doing some crazy jumps, or just doing some exploring.

We never went out in the desert alone, especially when camping, and there were times we were lucky we had company due to breakdowns and injuries. The possibilities around there are ENDLESS. Really spoils you.

However my wheeling is a different story. I'm almost always solo, and did some really remote stuff back then (80's-90's). If I can get this CJ to a point where I trust it, I may try to form a club in our area and setup some outings and events. Talked to a guy in a nearby town who wheels as well, but he races the big events and spends his time more focusing on that than anything. He'll be racing in Lovelock, Nevada this weekend.

Regarding your fuel pump, if it were me I'd make sure it's pretty solid. Worth the investment. If it goes south on you there's no getting home, or anywhere close for that matter. Might want to carry some type of spare, just in case. The pump in my 6x6 Polaris Ranger went bad out in the woods (original pump) but I was able to free it up to get us home. Bought a cheap Amazon replacement and it failed within an hour, but I was close to home so walked back for the original pump and some tools and it got me home. Ordered a much better pump and put it on, but left the old, original pump in the rig should the need arise again.

Happy trails!!

 

As a general rule, 7 PSI is max for a carb. Some carbs want even less. 10 PSI at idle or low RPM, you'd probably overpower the needle & seat and get flooding.

 

I forgot to mention, I left the electric fuel pump on the Jeep and it's still wired up with a switch. No fuel line and capped the ends to keep dirt out. The idea is I can switch to that in an emergency.

What I'm taking away from this is around 5 psi at idle and maybe up to 7 when RPMs are up.

Thanks for the input. May save me a desert walk so I appreciate it.

 

Trail report.

I'm basically back to a stock setup front to back. While driving on highway, pressure was around 5 psi and vary based on engine rpm. This makes sense. However, when crawling the pressure would shoot to 10 psi and it would sputter and run like crap. I think I know why. Crappy aftermarket pump is making good pressure but not regulating it well. At crawl, usage is very low and supply is still good with poor regulation.

I added the fuel pressure regulator back into the equation and took it out for 3 hours. Ran great. Pressure stayed at 3 psi for entire trip in all terrain. Engine runs really well at this psi. I finally realize how important fuel pressure is.

The fuel pump was fairly inexpensive so my advice is to get a good one (if you can find it). Maybe go electric.

 

Im looking for a little help with this subject as well.I am trying to set up my 69 CJ-5 225 Dauntless with the stock under seat fuel tank set up. The problem I keep running into is that my stock under seat tank has the 6 hole sending unit which doesn't allow for a return vent. When I search for the stock mechanical pump it has 3 outlets, Fuel in, fuel out and 1/4" vent. I have the 2 hardlines that run along the head to the pump and the other is the vent line but I can't figure out how the "stock" set up was.

My current set up is Fuel Tank >>> Rubber hose >>> Hardline from bell housing along head to pump >>> Rubber hose 5" >>> Pump

Any pictures or advice would be appreciated.

 

I believe you have the wrong tank. You could probably add a return line to it.

 

The under seat tank should have a bottom pick-up with j shapped tube inside an inverted flair fitting and a slightly larger npt drain in a small sump. The drain would be ok to use as a return. It's better to return from above so the fuel level doesn't affect the return in pressure.
The sender could be removed and tapped. It's a bit of a can of worms to add directly to the tank if you aren't used to working with fuel containers or like having eye brows.

 

69 would have a fuel tank with the supply and return lines going through the sending unit on top of the tank.

 

You would think so but my '69 doesn't and it sure looks like it's the original tank.

 

It looks like a very small window of time from flanged sender to the tank being put in the rear. Interesting.

 

Mine is an early '69. Pre-side markers and pre curved top windshield. My guess is it was a running change somewhere in middle of the 1969 model year.

 

This must be the case. Dad's 69 has the curved top windshield, hood mounted side reflectors, and the flanged fuel tank sender. Evidently lots of little changes in 1969 production.
So the question is, how to do a return line on the earlier style tank? I thoight all Dauntless CJ's had the 3 line fuel pump with return.