Odd Starting Issue: '98 4.0 Disco I

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
'98 Disco with evap. This is the one I need: https://www.lrdirect.com/WFX101020-Pump-Fuel/?keep_https=yes

But, I'd love to go the route of what you linked. Or... where do you go for $70 versions? Would that work for this system? (Not sure how to check things like that.)

Yes, they do seem tolerant of it, I've rode out weak pumps for a long time before. But when it breaks down on my son with nothing but air in the line, something is up with the fuel system. The key to getting the truck to start is to run the pump for a bit, then pump the pedal while turning it over. Just like when out of fuel.
 

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
Right, and I have metric flare wrenches, but they won't fit. The open end is not big enough to fit over the line to slide down over the nut. The rubber hose portion is the first block, but the crimped pressure end is what really stops it.

I've worked out an alternative. I'll post tomorrow when finished, and after I test to see if the new fuel filter helps with the original issue.
 

Uncle Douglas

Well-known member
Callsign: delete
IMG_20200818_082732.jpg


Keep one of these in stock. Has been the fix for most of the $300-$900 96-99 D1's we have picked up over the years. Instal them just so we can make sure engines are good runners because they have usually been sitting for years unstarted because of no fuel pressure. Airtex pump is typically in the mid $30's my cost.
Direct replacement kit for the pump in your disco's tank.
 
Last edited:

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
View attachment 14285

Keep one of these in stock. Has been the fix for most of the $300-$900 96-99 D1's we have picked up over the years. Instal them just so we can make sure engines are good runners because they have usually been sitting for years unstarted because of no fuel pressure. Airtex pump is typically in the mid $30's my cost.
Direct replacement kit for the pump in your disco's tank.

Very good. Thanks. No oddities in the swap once on the bench?

I've completed the cut-out and re-build of the line and install of the filter. Idiotic that I had to cut it out, but whatever. So far, I might have got lucky and fixed the odd start issue. Have to wait for a few start cycles to be sure, but even with a mostly empty fuel line, it certainly started much quicker and more decisively this time around. Whether this fixes the random miss-fire will be a longer shot, and who knows... Just have to wait for the light to come on again I guess.
 

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
OK. The bad staring issue was back by morning. So either it is bad fuel flow, or ignition. Since it starts perfectly if you cycle the key once or twice to build pressure in the line, I’m thinking it is a fuel issue still.

Based on my conversation with my local witch doctor, I came back home this evening and tried to see if I could see bubbles and such in the fuel coming from the pipes.

While doing this, I’m pretty sure the pump finally gave out. while my readings yesterday were a bit iffy, but maybe within the range of still being healthy, today I noticed hardly any pressure when I tried to get fuel out of the line. It now only has 15-20 psi when running, and that is after three or four minutes. Turned off, the pressure goes to about 25. This is less than it should be, and less than it was yesterday. So I’m ordering a fuel pump.
Whether this will solve the misfire is another matter. But I know the car starts, runs, and drives perfectly if I get it the fuel it needs.
 

BarryO

Well-known member
These GEMS engines detect misfires by detecting crankshaft speed variations via the CPS. Inconsistent fuel delivery could cause that.
 

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
Yeah. Doug agreed with me on that when I was over there today. I was just guessing, of course, but it makes sense. Maybe I’ll get lucky and the two issues will be solved with the new fuel pump.
 

BarryO

Well-known member
I'm just guessing as well.

Doug spent a long time chasing misfires on my 90. Turned out to be an air leak in the input plenum.
 

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
Really? Even with only two contacting sides? That's the main reason I stripped the nut with the 5/8 wrench. Looks like something for the Christmas list.
 

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
So what’s the secret to pulling apart the fuel pump to replace the motor? What do you do to get the hoses off without breaking something?
 

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
Also, will I be able to find one of the pick-up screens/bags for the bottom of the pump from NAPA or someplace?
 

pmatusov

Technical Excellence Contributor
Callsign: AK6PM
The kit (E3270) should have the pickup sock included.
The bottom can comes off easily - it has four spring clips that need to be depressed at the same time, so a third hand helps.
The plastic hoses in the factory pump rarely come off nicely - make a slice in the end of the hose along the plastic nipple and pull it off. Don't bother pulling that accordion hose off the pump motor - it's junk already. The piece of rubber hose included in the kit should replace it - but you may have to play with the length, so the pump can move up a little. Pay attention to how you place the hose clamps - so the wires don't chafe on it.
 
Top