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I just checked a couple things…
1. Voltage to pump is 14.2 V. Higher than needed. Running same as alternator voltage output. Should I check on this further?
2. Fuel pressure right at TB inlet is 11psi. This is with a 100 psi gauge, so accuracy is not so great. Pressure didn’t change with high rpm. It even stayed at about 10psi when I pressed the pressure release button for the dump hose at the gauge at high rpm.
I drove a mile or so, after warmup, and it sputtered on acceleration like it has been doing. Checked V and psi after driving too, and numbers were the same.
I’m thinking pump is ok.
Any suggestions?
I just checked a couple things…
1. Voltage to pump is 14.2 V. Higher than needed. Running same as alternator voltage output. Should I check on this further?
2. Fuel pressure right at TB inlet is 11psi. This is with a 100 psi gauge, so accuracy is not so great. Pressure didn’t change with high rpm. It even stayed at about 10psi when I pressed the pressure release button for the dump hose at the gauge at high rpm.
I drove a mile or so, after warmup, and it sputtered on acceleration like it has been doing. Checked V and psi after driving too, and numbers were the same.
I’m thinking pump is ok.
Any suggestions?
I'm late to the game posting any responses to this, but 10-11 psi seems way too low for a TBI (or any fuel injection) system. Most fuel injection systems need 42-58 psi (my TPI system requires 58). You need the higher pressure at the input to the throttle body, then the Howell system has a regulator built in where it regulates the pressure down to the right amount to go to the injectors themselves. But even the injectors will need more than 10 after the regulator I believe. When cold, the system will have the IAC (idle air control) valve mostly closed (like a choke limiting air flow) and then open up with temp increases. So with more air at higher engine temp, your system may be running way too lean due to the low fuel pressure, hence the sputtering. I believe Autozone and O'reilly both will loan you (with a refundable deposit) a fuel pressure gauge to test for sure since you're not 100% reliant on the accuracy of the gauge you're using. But even with a questionable gauge, that seems so far off to me.
If you feel quite sure the fuel pump is OK and has good voltage, then time to check for other potential restrictions in the line. In-line filter, sock filter in the tank, pinched/kinked metal line somewhere, etc.
I ask because you said you go half day worth of running before it starts to be un happy which leads me to suspect a heat soak issue like over heating ignition module(under the cap in HEI) or hot fuel pump
I would not initially suspect IAC but maybe it could also be getting heat soaked and stuck
Thanks Gents.
Yes, I do think it could be heat/warmup related. Maybe a signal issue from the ignition. Maybe a Coolant Temp Sensor issue. Maybe an expansion issue with the manifold and/or gasket.
It's funny though, because it was a very cool day the first day it happened. Everyone was bundled up because it was about 50 degrees for the high. Still have the OEM temp gauge, so I have no real way of knowing what the jeep was really running at. Never got far off the "C" though. Coolant system is all new/refurbished.
I think I'll call Howell and see what they have to say as well.
4-13-23:
-In Moab, when flexing over obstables, the rear tires rubbed the rear lower corners of the wheel openings a bit (common problem with CJs and bigger tires). So, I removed the flares and laid out a tape line to cut/trim the sheet metal a bit at the lower corners. Will probably re-install the OEM flares for now, after some trimming to those too.
-Called Howell support and spoke with Troy. Gave him my issues and numbers so far. He said the pump and voltage are probably fine. But, he suggested it could be a signal issue from the ignition, or it could be an O2 sensor issue, or it could be something else. He suggested I get a scanner of some sort to read the data through the ALDL port. He suggested a cable from WinOBD and to just download their free software on a laptop. So, I ordered the cable ($80 on eBay) and await it's delivery.
CJ7 Reman 258, Np435, twin stick 300 dana, Currie 44's both ends with DetroitTrac both ends and chrome moly 35 spline shafts, Maxis Razor 33;s Gps based speedo.
A literal barn find CJ7 I recently purchased from my Father. Has been sitting in storage since 1998. 80,000 miles and all original, except a re-paint job back in the 90s.
My plan is to clean/repair/replace every "system" in order to get it back up and running.
Systems worked on thus far since April...
-Cooling: New water pump, t-stat & housing. All new hoses and fittings for the heater hoses at the intake manifold. Radiator taken to shop for cleanout and rehab (still waiting on it). New radiator hoses and cap.
-Fuel: Dropped fuel tank to clean out/flush. New rubber hoses at top of tank. New filler & vent hose at tank. Tore off the Carter BBD carb (what a train-wreck that thing is!!). Beginning the install of Howell TBI system. Replacing all vac lines.
-Oil: Oil change and filter change. Replacing valve cover with new Aluminum unit and new Felpro silicone gasket (still waiting on correct Gasket).
I'm selling take-off items as I go, such as...
-Hard top
-Hard doors
-AC system
-Steps
-Bumperettes
-Console
Fun so far. This is my second CJ build, but it's been about 25 years.
May 1:
-Intake gasket replaced, because I thought that was the culprit. Still bogs down and sputters. Next!
-Per Troy with Howell, I unplugged the MAP sensor to see if anything changed while running. Still ran crappy, so that's a pretty good indication that something is wrong there. So, I ordered a new MAP online, GM #16165793. We'll see how it goes.
Right! And, I find it interesting that the mounting distance away from the TB for the MAP is critical too. Howell states to mount it on the firewall in my instructions. But recently, they told me it needs mounted as close to the TB as possible, like 3" away.
I guess it's probably a good idea to gather up spares of things, like MAP, O2, CTS, TPS, Fuel Pump, Filter, etc.
Right! And, I find it interesting that the mounting distance away from the TB for the MAP is critical too. Howell states to mount it on the firewall in my instructions. But recently, they told me it needs mounted as close to the TB as possible, like 3" away.
I guess it's probably a good idea to gather up spares of things, like MAP, O2, CTS, TPS, Fuel Pump, Filter, etc.
May 8, 23:
Been working quite a bit in hopes of solving the sputtering issue I'm having...
-Replaced Intake Gasket. Didn't solve problem.
-Replaced Thermostat because Jeep temp gauge would barely rise when warmed up. It replaced a new T-stat I put in last year. Checked out the gauge and Sender unit. Put in new Coolant Temp Sender unit but gauge checked out fine. I was told that the computer might be confused if the coolant temp never got warm enough or wasn't steady enough.
-At the same time, I also replaced the MAP Sensor after some trouble-shooting.
-Just for the hell of it, I replaced the Injectors as well. The spray didn't seem quite right, as compared to my brother's spray pattern on the unit on his '69 Bronco.
Result of all this is the Jeep runs GREAT now!!! I believe this is one of those deals where a combination of items was contributing to my woes.
For now, the Jeep idles great, the temp gauge goes up to about 1/3 level now and it accelerates wonderfully.
-Have the old injectors and was thinking of checking/cleaning them somehow. It'd be nice to have some spares, along with various other spare items.
-Next on the list...
a. Re-upholster driver's front seat bottom.
b. Front roll cage.
That would be interesting, you would need to be able to provide12-15 psi fuel/injector cleaner to it and 12v hot and ground and run them til their cleaned out, I would think a similar rig to the ones that you see on YouTube
