Fuel Pressure Question

cmeuzelaar · Dec 13, 2004

Hello all,

A couple of months ago I replaced my fuel filter on my '89 Cherokee Laredo. According to procedure, I went to the fuel rail to bleed the pressure. To my surprise, I had no pressure (Jeep had been off for a few hours at this point). My question is: is there a check valve on the fuel line that is supposed to keep the rail pressurized?

In part I'm asking b/c it takes a long time cranking to start, but if I turn the key to Run and let it sit until the seat belt light goes off, it fires up pretty quickly (still not that fast, but faster--5 seconds of cranking versus 15). As I need this vehicle to last me another 2 years or so and it's both my DD (in winter, in summer a Honda Shadow is) and frequently the vehicle I use for family trips, I'm trying to find and fix things like this.

Thanks,
Chris

'89 Cherokee Laredo, 4.0L, Auto, 240k

Matthew Currie · Dec 14, 2004

cmeuzelaar said:
Hello all,

A couple of months ago I replaced my fuel filter on my '89 Cherokee Laredo. According to procedure, I went to the fuel rail to bleed the pressure. To my surprise, I had no pressure (Jeep had been off for a few hours at this point). My question is: is there a check valve on the fuel line that is supposed to keep the rail pressurized?

In part I'm asking b/c it takes a long time cranking to start, but if I turn the key to Run and let it sit until the seat belt light goes off, it fires up pretty quickly (still not that fast, but faster--5 seconds of cranking versus 15). As I need this vehicle to last me another 2 years or so and it's both my DD (in winter, in summer a Honda Shadow is) and frequently the vehicle I use for family trips, I'm trying to find and fix things like this.

Thanks,
Chris

'89 Cherokee Laredo, 4.0L, Auto, 240k

Yes, there's supposed to be a check valve, but unfortunately it's in the pump itself, which means that you have three options: A new pump, a line-installed check valve from some other source, or to keep doing what you're doing - wait, or if it gets really bad, turn the ignition off then on again to force the pump to cycle twice.

If you do a search of the archives, you might come across something about the second option. I think there's a BMW check valve that works. I have stuck to option 3 myself.

Remember too that no matter how well you fix this problem, an 89 will crank 4 engine revolutions before the ECU sends out a spark signal. It will never start instantly.

cmeuzelaar · Jan 17, 2005

Does anyone know any more details about this phantom BMW check valve? I'd really like to put it in since my fuel pump pumps fine, it just won't hold pressure once it's off.

MJR · Jan 18, 2005

First off the check valve is to hold fuel in the line not really pressure. It's when the fuel drains back into the tank that it takes longer to start. Here is the old post on the check valve.

"The BMW fuel check valve part number 16 14 9 068 988 fits between the filter and the fuel rail since its connections match this section of fuel hose. I installed one a couple days ago and it works fine. The unit comes with about a foot of 8mmx13mm fuel line, hose clamps, insulation and plastic nut covers for $3-5. It is necessary to make room for the valve, but that is not hard. Call a dealer and order one, or it may be in stock."

Fuel Pressure Question

cmeuzelaar

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Matthew Currie

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cmeuzelaar

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MJR

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