1993 RT/10 Long cranking when starting/ fuel pressure issue

pincrusher311

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I know this is a very common issue for the Gen 1, but I have replaced everything thing on the fuel pump and the fuel filter already and still having fuel pressure issues. I have about 9-10 PSI while cranking and around 50 psi in idle. I am not able to find the post on about the DIY timer thing people said that has worked on their car and easy to install. Does anyone have any links they can share? Any insight would be very helpful to me. I have the tank and pump pulled out right now and looking for options. Has anyone had trouble with the fuel line from the pump to the regulator being bent? Has anyone installed an aftermarket accessory fuel pump? Thank you for your time and insight.
 

Chad Spackman

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Old thread but I thought I could share may experience in going after the root cause of this issue. If you have long crank times and you have confirmed it's due to fuel bleed down, the most likely cause is 1) the check ball within the fuel pump, 2) (or more likely) the pressure regulator leaks. Anything else is outside the tank and you'll probably be able to smell it or see it. The fix for 1 or 2 involves removal of the fuel tank. Something I was reluctant to do because I've heard its a nightmare involving grinding material away etc etc. It's really quite and easy job and its worth doing if you want things back to normal. A lift is a big plus. This applies to Gen 1 RT/10s


0) run the tank down as low as is practical
1) Remove the fuel tank cover on the front facing wall of the trunk. The steps are:
a) unclasp the wiring harness above the tank cover
b) Drill the center out of the rivets (3/8 bit) which are around 3 sides of the trunk cover (both sides and bottom)
c) push a 1.5 inch putty knife around those 3 side to break the seal. This is easily done and with a little care you'll not damage a thing.
d) The cover will be able to be removed. (It'll be dusty in there)

2) loosen the 2 tank band nuts at the bottom of the tank, enough to unclasp them. The same clasps (without nuts) are at the other end of the bands and the bands may be removed now by lifting the bands and wiggling them a little. (They are easily re-attached later when the splash guards are off)

3) The next steps are to gain access to both side of the tank and disconnect it for removal. There are 4 connections plus the filler tube. Fuel out and tank vacuum are on the left. Tank vent is on the right. Filler tube is on the right. Electrical connection happens when the tank is 1/2 way out.
a) Remove gas cap. Remove paint protection flap. Remove the 3 screws the flap exposes.
b) Lift the car and remove rear tires.
c) Remove battery cover at the bottom of the left splash guard
-- 4 bolts bottom of left rear bumper
-- 1 bolt near these bumper bolts into frame
-- 3 bolts into rear splash guard
-- 3 screws into bumper cover
Disconnect negative battery terminal
d) Remove left rear splash guard
-- Remove all plastic push pin fasteners. Drill out rivets on quarter panel (just the front one and back will do, but I do them all)
-- Work from each edge. Use a hard plastic pry that won't hurt your paint, and work the splash guard out. Moving to the top as the last part to remove. That was the hard part. You have to do the right side of course. Basically same thing but no battery cover.
e) Remove right splash guard

4) Remove tank vent tube
a) Under right fender, Compress clamp closest to you which comes off the filler neck
b) work the vent tube off

5) Remove gas filler tube
a) move tube in and drop it out of the gas cap hole
b Rotate 180 degrees and work it out of the tank

6) Siphon remaining gas out of tank through the now open tank. The lighter the tank the better

7) While (6) is going, go to the left wheel well and disconnect vacuum line at the junction near filter

8) Disconnect filter from fuel high pressure line (you don't have pressure in the line or you'd not be doing this :)
-- spray junction with WD40
-- rotate sleeve and tube back and forth a bit
-- Push tube into filter
-- Push sleeve into filter with adjustable wrench while pulling on fuel tube

9) Remove EMPTY tank
a) Go over to right side and move tank back guiding filler hole through the trunk wall
b) Go under the car and you'll be able to push the tank past frame member
c) Go into the trunk and pull the tank far enough out that you can see the electrical connector
d) lift the clasp and disconnect
e) Remove tank all the way. It needs to point down a little at the end of travel out

Installation is the reverse of everything with one exception. Once tank is back in place you want to reinstall the bands while splash guards are off. You can get to the fronts of the band clasps from the wheel wells. Have a look at them before you put the tank in so you know what you are trying to achieve. Reconnect the bands and tighten the nuts.

I would run the car before reinstalling splash guards and check for leaks.

Pump removal etc will be in another post if this is at all of interest to anyone.
 
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redtanrt10

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Nice write up, thanks!! I'm over due and found out the only way to address the regulator is via tank removal

How long did the process take for you?

thanks, Mike
 

Chad Spackman

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The first time, it took me most of a day to get it out. Since my fix seemed to change nothing, I did it a day later in about an hour (which did not include the trunk panel). The speedup mostly came from learning how to take the splash guards out.

Now why twice? So the first time I identified the regulator as the problem. It leaked back through the over pressure return under no pressure at all. I replaced it but in the process changed the fuel tube between the pump and the regulator. That was a mistake I'm still fussing with. The pump has a 3/8 inch barbed tube connector on it. The regulator has a 1/4 inch connector on it. And the the fuel hose is hard stuff. A leak has occurred at the 3/8 junction. (I now pressure test before putting it all back) and I'm yet to solve this, totally simple and really frustrating problem. I'm waiting for a truck to arrive as I write... with, new hose, new M12x1.5 fuel pump barbed adapter, new cinch clamps. I'm hoping never to see this fuel tank again :). I think I've nicked the barbed adapter. If that's not it, I'm going to go for some more pliable fuel hose.

THE PARTS JUST ARRIVED!!!
 
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Chad Spackman

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Ok!!! Pump module is back together. I used 1/4 I.D. polyethylene clear tubing. I understand from some reading that polyethylene is "good" but not "very good" for gasoline. I put the tubing over the 3/8 barbs using some almost boiling water. 2 cinch clamps at each end of the tubing. Pressure test and it's quiet. Back to the car tomorrow.
 

Chad Spackman

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One additional thing I'd note is: getting from tank on the ground, back to a point where you can test it, is all of 10 minutes. Slide the tank 1/2 way in and insert pump & level sender connector. Slide all the way in and connect vacuum line and fuel out line on the left. Then the filler-tube and vent on the right. Reconnect battery. Put in a couple gallons and start. I started up, then waited an hour and restarted. So far so good. I'm letting it sit for a few hours and will see if it's really fixed
 

Chad Spackman

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I thought I'd update this since Ive made some mistakes and it has caused me some headaches. The first lesson. Don't use polyethylene for fuel pump hose. It softens. Mine split at the pump right where the clamp was. Fortunately and miraculously, it happened in my driveway. My new avatar is a picture of my brother towing me a 1/2 mile down to my shop to fix it. A sign of things to come. I found some decent nylon braided, steel reinforced, hose. (Im embarrassed to say where I got it). Put back together... and... pressure would bleed down after about 5 minutes (the problem I was originally trying to fix). Back apart. The problem was that a good seal at the pressure regulator with a hose that has to fit the 5/16 pump barbs, and the slightly less than 1/4 inch pressure regulator, is a tough ask. So, I got some pliable and thin polyurethane fuel hose and put an inch of it over the pressure regulator barbs, fattening it up for the 1/4 inch, steel braided hose. This was a tight fit and was done with a hot air gun. Then I put the steel braided hose back over that, (also a nice tight fit) and clamped with a steel crimp. Back together. Pressure held. Done. 2 weeks later cruising north on rt95, on a spectacular day, and brrrrrr... Engine dies... a tow truck pulled up in less than 5 minutes. Sheer luck. He tows me back to my shop (84 miles). Tank back out... (I'm getting good at that). The outer hose and clamp slid away from the pressure regulator leaving the polyurethane, and then the polyurethane, now with no clamping pressure, popped off the regulator. If you read about the pump module in the shop manual, you'll see they say that if the pump fails, you have to replace the entire pump module. One look at the module and you see that it is easily disassembled with each and every component assessable for replacement. Never made sense to me that you'd replace the entire module. (If you can find one it'll cost more than $1800). But I think the reason they say replace, is this interface from pump to regulator. The combination of the 2 different size hose barbs (pump and regulator), and the fact that the barbs on the pressure regulator are smooth enough to be non-existent, makes the connection a reliability issue. They make that interface with very hard poly, non-pliable hose and some heating process I guess. Next... I go talk to Jeff Palmer at D'Ambosio dodge (a super viper mechanic). He hands me 1 foot of hose and tells me this will work. I put it back together. I'm hesitant to go anywhere :) The real fix is going to be next. That is, put that silly pressure regulator in the trashcan where it belongs. Come off the pump into a properly barbed 4AN bulkhead connector, allowing both ends of that hose to be the same size and type. The bulkhead connector goes through a newly drilled hole at the center top of the module. Using a 4AN to 4AN hose and fittings, run this to an external, return type, pressure regular. Run the return back to where the old regulator was, also with 4AN to 4AN hose and fitting. Another bulkhead fitting in place of the old regulator takes the return fuel back to the tank. Lastly, a 4AN hose from external regulator to 5/16 Quick Disconnect connector at the normal fuel filter. The question do I do that, or just go drive. I'm doing the latter. 3 hour trip south on 95 today... Yikes!!
 

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