Engine/Transmission (1994 - 1998) Fuel Lines on my '96

[MHalloran]

Hey Guys,

Just replaced supply & return lines to fuel tank with marine hose. Old supply line running along frame under cab started leaking due to corrosion so I replaced both from engine up to the point on the frame just before the tank. ( you know you can't access this section easily without dropping the tank, didn't want to do that, half full ). Since finished, engine still doesn't want to start easily. Cranks,cranks, then starts rough. While under the truck, I also eye-balled the sending unit on top of the tank. ( you CAN get your head up in there ). At the spot where the supply & return lines enter the tank is also rotted to where the pair of them are loose and kind of laying there together. My question is, would this rotted away connection on top of the tank also create a hard start? Should the tank be somewhat pressurized also for correct operation? (no leaks?). Napa says the sending unit is a dealer item only (ouch). Don'y want to buy it if I don't need it but if it fixes the problem, I'll have to. Everything else visibly in fuel system looks OK and filter is new. Haven't touched pre-heater yet either. Any input would be appreciated, winter's coming. Thanks very much. Mike

 

[xpetecx]

Im going threw the same thing with my 96. I dropped the tank and found that all of the metal line were rotted realy bad. The Previous owners of my truck got alot of mud on top of the tank so even the little lines going into the tank are rotted off.



As you stated above the fuel tank module and sending unit are dealer only. Im kinda at a stand still my self so I will be watching this thread closely.



If I find anything out I will be sure to let you know.

 

[Joe G.]

The sending unit should not cause a hard start, it's inside the tank. If the fuel module (I think this is what you mean by sending unit) pipes are bad that could cause your problem. If you can use a mirror and a flash light to look at the pipes and connections on top of the fuel module. If they are bad they can certainly cause a hard to start problem. The lift pump does not do a good job of pumping air. If you have an air leak in something you may not be able to see it. You may have other fuel supply system problems. Email me at -- email address removed -- for my write up on the 12 valve fuel supply system, how it works and how to fix it.

 

[MHalloran]

Im going threw the same thing with my 96. I dropped the tank and found that all of the metal line were rotted realy bad. The Previous owners of my truck got alot of mud on top of the tank so even the little lines going into the tank are rotted off.



As you stated above the fuel tank module and sending unit are dealer only. Im kinda at a stand still my self so I will be watching this thread closely.



If I find anything out I will be sure to let you know.

xpetecx,

My supply and return lines going into the are rusty but not rotted off as bad as yours sounds. The piece that holds them together (about 1. 5 inches in dia. ) actually what is loose from the tank. I sent Joe G. an e-mail. Waiting for his reply. Also if you should discover anything else wrong on yours, let me know. I'll do the same for you. Thanks. Mike (thanks to Joe also)

 

[JFaughn]

Put about 3-5 lbs air pressure in tank then use flashlite to look for leaks , your not going to see fuel leak on a vacuum - lines from tank to pump sucks /not blows .
Also check fuel pressure .

 

[djreed]

I replaced the fuel level on my sending unit and found the easiest way to check the top of your tank is to unbolt 8 bolts on the box and unplug the harness in the back and three screws on filler neck. 2 guys can lift the box and move it back. The box is very light. I had a full tank in mine and didn't want to drop it. I know this don't help your problem but can save you some time.

 

[MHalloran]

Put about 3-5 lbs air pressure in tank then use flashlite to look for leaks , your not going to see fuel leak on a vacuum - lines from tank to pump sucks /not blows .

Also check fuel pressure .

JF, I wouldn't be able to put 3-5 lbs. in tank because of my corrosion problem around the supply/return lines going into tank. Rotted out. Thanks anyway.

 

[MHalloran]

I replaced the fuel level on my sending unit and found the easiest way to check the top of your tank is to unbolt 8 bolts on the box and unplug the harness in the back and three screws on filler neck. 2 guys can lift the box and move it back. The box is very light. I had a full tank in mine and didn't want to drop it. I know this don't help your problem but can save you some time.

djreed, yes, this technique I will consider because 1) tank about half full & 2) tank hanger bolts are somewhat rusty (like everything else underneath :{) and would rather not touch them. These box bolts easy to get to? I haven't looked yet. Thanks !

(isn't it a shame how the truck itself rots out :{ but our engines we cannot kill. CUMMINS lives. )

 

[xpetecx]

MHalloran, Ive got a vew devlopments if your interested.



I ordered a vulcan draw straw for the 98 to 02 trucks. I talked to Vaughn MacKenzie who has one on his 98 12 valve. I know your lines going into the tank are not rotted but this might solve the problem with how they sit in the tank for you.



Also you might want to check with the dealer on just getting the gromet that holds the lines. I was there last week getting the lock nut and gasket that hold the whole fuel module in. I think you could get just the gromet that holds the lines in but not the lines.



Also I went to make new steel lines for my truck, was going to make double flares with couplings. Well I couldnt, because the factory lines must be metric. I had already bought the lines, and wasnt going to try and find the metric tubes. So I just put a bubble on the lines I had, to help a hose clamp grab the tube.



Hope some of this helps.

 

[MHalloran]

xpetecx,

I will definitely check with the dealer about this gromet. I'll go there Monday. Hopefully ,if I can buy just the gromet, they'll be honest about it & tell me I can & not try to sell me the whole module. Always have been leary of dealerships 'cause we all know that they look for the $$$ to take from an un-educated customer. (which cummins owners are not). Also, where'd ya get this "draw straw " & hows it work?

Dude, I'll keep in touch with you. Mike

 

[xpetecx]

I dont actually have it yet. I ordered it today even. Ordered it from here http://www.vulcanperformance.com/servlet/.91fd5e5c/the-125/<i>Draw-Straw<-fdsh-i>™/Detail

 

[MHalloran]

I dont actually have it yet. I ordered it today even. Ordered it from here <i>Draw Straw</i>™

xpetecx, did you call them about this item? It says it was for 98. 5 -06 trucks. Didn't see draw straws for the older models. Yours is a 96 like mine,is that right?

 

[Vaughn MacKenzie]

Their website shows 24-valve but when I talked to Vulcan they said they fit the 12V also. The fuel pickup is the same from '94 or '95 through '99 at least, it was changed slightly for 2000.

Vaughn

 

[xpetecx]

yes my truck is a 96. I guess I will know for sure once the draw straw gets here. Although I dont think it will be an issue.

 

[djreed]

The box bolts easy to get to. I don't remeber what size they were air impact a 6" exstension and they come right out. When you do take the box loose there will possibly be some shims to deal with but they are nothing.

 

[MHalloran]

Today I pulled out the overflow valve and measured the spring. A little less than 1/2" in length so I carefully adjusted it back to about 0. 55". Put it back in,gave the lift pump plunger a few pumps, turned the key and she started right up. I thought, no, this was too easy. Let the truck sit for a half hour, turned key again, back to hard start with white smoke. From there went to the well known pre-filter/heater. Inside of bowl had some sediment, but not too bad. Then removed the heater element, drilled rivots out (don't plan on putting it back) to see if it was burnt and yes it was. (thanks to Joe G. , who has a spectacular write-up on our fuel systems and what to look for). Then pulled off the small molded hose (never replaced it yet) that goes to the lift pump. From there, went to dealer to order this new hose and to ask about the fuel tank module. You need truck VIN # to order new module and they told me it would be in the $300-$400 range. Ouch. Then they surprised me & said I could order individual parts needed and not the whole module. So tomorrow when I go back to pick up the hose I'll order the part to replace the rotted supply/return fitting I need on the existing module. Djreed, this weekend I am going to pull the box off, picked up 8 new metric bolts to replace the old rusty ones with and hopefully by the end of this coming weekend I'll have my hard start issue resolved. I'll keep you guys posted. Thanks for all the replies. Any other ideas are welcome. Mike

 

[MHalloran]

Hey Guys, went to dealer today to pick up ordered hose and hopefully order needed fitting for fuel module. Well, I guess the guy (inexperienced) behind the counter meant well when he showed me the exploded view yesterday of the fuel module and told me I could order parts. But obviously I found out he was wrong. The picture was of a gasser module, not a diesel (and I had stated to him yesterday it was for the diesel). Turned out, I had to buy (no choice) the whole module . $340. They even had it in stock. You can tell by the new one on how its put together that you really wouldn't want to try and replace parts on your old one. Also, since it's not in a fun spot to get to, I figure all new will be piece of mind. Keep you posted on the install and the hard start issue in a few days. Comments welcome. Mike

 

[MHalloran]

update

Box (bed) has been lifted, new fuel module in place, new Larry B fuel lines from tank to engine, new fuel filter, cleaned pre-filter and scrapped heater element, new 90 degree molded hose on lift pump, existing overflow valve still in place (spring length is OK) although new one purchased will hold as spare. Cranked and started right up. Ran fine. Next day, started right up no problem. :-laf. Gonna leave the bed off until the exhaust system I ordered comes in and I install it. Easier to do while standing, I think. Just wanna thank Joe G. and all you guys for the input and help. Couldn't have done this without your help. Thanks again. Mike