Fuel Pressure Question

60 Biscayne · #1 (**permalink**) 03-08-2008, 08:49 PM

Here we go again!
2004 4.0 Shop Manual says Fuel Pressure should be like 49 +/- 2 lets say 50
We stuck this 2004 engine into a 1989 Wrangler that was a 4.2 with a carb!
We used the same 89 fuel tank which has NO Pump in the tank
We installed an 80's vintage Ford truck in line Hi Pressure fuel pump (E2000) and it put out like 75+ which is "to high, I'll blow the gaskets out etc"
So we installed a 1998 Grand Cherokee Fuel Filter/Regulator
I now have a Pressure reading at the fuel rail of about 35 - 37
The engine seems to run fine, I have other items to complete before I take it for a ride but it idles nice, responds well etc......
What are the ramifications or problems I can expect relative to not having the optimum fuel pressure (35 vs. 50)
Should I chuck the Cherokee regulator (that I just bought) and buy an adjustable one (0 to 85) which are available on eBay.
Any help is appreachiated.
Thanks,
Jim

yjdave · #2 (**permalink**) 03-08-2008, 11:58 PM

The pressure seems ok @ less than 40. Any extra should run back to the tank. The stock pumps work on pulsing current from the relay. What i see is the pump might over heat not being in the tank. I did the same thing as you about 7yrs ago and did a HP external pump and it only lasted maybe 8-10 months and burned up. If you can find a sendinging unit w/pump or the whole tank w/ everything that would be the better option. (not fun trying to get home w/ shoot fuel pump)

60 Biscayne · #3 (**permalink**) 03-09-2008, 09:21 AM

Yeah, I hear you about the pump overworking etc......
Brings up a couple of other points, maybe another topic also, I had to close off the return line completely! I had zero fuel coming up to the fuel rail with it hooked up??? The next wierd thing: This filter regulator gizmo has one nipple marked "OUT" which would make the other two you would think to be IN & RETURN - well the only way this devise works is with the OUT receiving the fuel from the Pump, the Return Blocked Off (as I said) & the other Nipple send the fuel up to the engine..............Weird! You know how many times i switched things around, clamp off this & try that...............
My buddy has a buddy that has a 2002 Wrangler that's going to junk!
He's sold off the 4 cyl engine & I got the radiator out of it.
New Topic - Maybe?
Will the 2002 tank fit into the '89?
Will the 2002 4 cylinder fuel pump be the same as the 4.0 setup?
Thanks,
Jim

yjdave · #4 (**permalink**) 03-09-2008, 02:08 PM

NO..on the tank.
maybe on the pump. not sure of the differnence between 4-6 cyl. You can find them all over @ yards or ebay. You need a return.

RBLUE · #5 (**permalink**) 03-13-2008, 07:24 PM

Standard fuel presser is 33 psi.on fuel rail.

redrooster · #6 (**permalink**) 03-14-2008, 05:55 PM

Woud have probably been easier to just by the pressure regulator from Summit for $100. See, this chasing ghosts thing will drive you nuts and here you are back to wanting to change the tank. Bottom line is, you need a pump, regulator, return and the proper fuel pressure. It doesn't have to be Jeep parts or internal pump to work. I would be trying to avoid putting older stuff on my 04 motor anyway. There's nothing wrong with the E2000 by the way, I've been running one for years. If it came from Autozone, that's another story.
Back to the fuel pressure thing. The link I pasted in one of your other threads said 45 psi. What it didn't say was where it was measured or if that was at idle or engine off. With the Jeep running, I would imagine that 33 psi might be adequate. Floor it and see if it sputters.
Also, I suspect one of your ports on the Cherokee regulator deal might go to a charcoal cannister. Pull down a fuel system diagram and see.

60 Biscayne · #7 (**permalink**) 03-16-2008, 08:24 AM

Hay Red - I'll look into the charcoal filter angle etc...
The bottomline right now is:
I'm not using the Littl Jeep until I get the wiring all squared away. I'm hooking up 5 individual Sunpro gauges: Temp, Oil, Amp, Vacuum & Fuel
The original Jeep gauges seemed to work whenever they felt like it or not at all - I have to get a 92-95 Speedometer so that we might be able to see how fast we're going etc........
The engine starts right up - sounds great & I ran it home like 25 miles+ & No Problems.............
When it was at the garage & after its maiden voyage up & over a nice size (3,000') mountain & back to the shop... left idleing maybe.....Anyway the pump started making a funny noise. Like it wasn't getting fuel fast enough from the tank vs what it was pushing out. I thought maybe we need another pump to supply the E2000 so that it works easier. If that would do it, I'd be on Easy St.
Silly Question: Would a late model like a 2004 in the tank pump fit / work in the older model (89 or 95) Fuel Tank? You see I'm thinking of trying to duplicate as much as I could the original 2004 set up. I have acess to a 2002 wreck & I could get the stuff from it at a fair price but somebody said that a 2002 tank won't work in a 89 - Didn't say why? Just that it won't?????
Thanks for all the Help etc......
Jim