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Fuel tank questions

Dumb A
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Dumb A

Dumb A

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02 ram 3500 5.9 Cummins. When I remove the fuel cap the tank releases pressure, is this normal? I looked for a breather for the tank but didn't find one. What I did find on the fuel module was a suction, return and capped 5/16 port. I removed the cap and attached a hose to it then blew into the tank. I could hear bubbling so I figure this is a auxiliary suction port? Dose this tank have a vent? If so where is it located. The reason for these questions is I feel it has a starting issue. In the morning, cold start, WTS, crank crank crank, short start and dies. Ignition off, back on, WTS, crank crank crank, starts and runs fine. This is 90% of the time. When warm crank crank start, always. The other 10% of the time it's ignition on, WTS, crank crank crank, crank crank crank, crank crank crank, start and runs fine. I have a new afe filter being shipped to me it is questionable. Lastly the fuel pressure gauge should be here next week, isspro AV-2. The electric fuel pump is on a manual switch. I turn it on and off. It is located forward of the tank. 

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IBMobile

IBMobile

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54 minutes ago, Dumb A said:

When I remove the fuel cap the tank releases pressure, is this normal?

No.  The vent on top of the fuel sending unit is most likely blocked.

 

54 minutes ago, Dumb A said:

The electric fuel pump is on a manual switch. I turn it on and off.

Install a relay, which is controlled by the ECM, to turn on and off the fuel pump; this will turn off the pump if in an accident.

 

https://mopar1973man.com/cummins/articles.html/24-valve-2nd-generation_50/51_engine/59_fuel/installing-protective-lift-pump-relay-r501/

 

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Dieselfuture

Dieselfuture

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post-1102-0-32196000-1422207073_thumb.jpg

My basket is modified but the vent is on the left, gray thing that looks like something should be blumbed in to it.

Also what is said above, put a relay to control fuel pump for safety reasons and easy starting. Try next time to turn you pump on for few seconds then shut it off then start the engine then turn fuel pump back on, it won't hurt the vp in that short time. If it starts easy you know the problem.

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Mopar1973Man

Mopar1973Man

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Should never vent air when removing the cap this mean the vent on the tank is plugged up. Just as shown the grey fitting is the vent and it does have a rollover valve too is if the truck is up-side-down then the valve will block fuel from draining. Very possible to have the valve plugged with mud which is common with pups that like 4x4 in deep mud.

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Dumb A

Dumb A

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I now understand what this port is, thanks. Now my question is how does this port let positive pressure out of the tank. Yesterday I removed the rubber cap from this port attached a hose and blew air from my mouth into the tank. I heard it bubbling in the tank. So I know it passes air one direction. This would be to prevent a vacuum or negative pressure in the tank. I didn't suck on the hose as I didn't want to drink diesel.

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Mopar1973Man

Mopar1973Man

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I've seen cases where the head was cracked and pushing compression gases back in the fuel by the return line. What I would do is check the return line for excessive air blowing through. There is a quick connector there near the starter and you can add a piece of clear vinyl tubing to see the fuel as it travels. You can use a long piece and route it back to the fuel tank filler neck. Then you can start the engine and watch for air being introduced to the fuel.

 

Usually a pump that is sucking air tends to lose prime quick after shutting down being the air continues to bubble into the line and return fuel to the tank dropping the pump prime. This would be seen after restarting as a sudden drop in fuel pressure to zero typically and then regains pressure within a few seconds typically. This is a air leak in the suction line typicaly.

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Dumb A

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Took longer than expected but this is what I found. I have air bubbles in the return line. I also found air bubbles and fuel escaping from #6 injector where the high pressure line attaches to the connecting tube. I tightened a bit but didn't seem to help. I also noticed a droplet of engine coolant coming from the head gasket just under the npt plug that I recently changed. I don't know if it is coming from the plug or the head gasket. My questions are do I replace one injector and connector tube or replace them all. The truck has 210K and I don't know if they have been replaced. I've seen people say that the 50 HP RV injectors boost HP and milage. I don't understand how that works? Where should I purchase them and how much should I spend. I'm assuming Bosh injectors? Once I get the fuel leak stopped I should be able to tell where the coolant leak is? It is running down the outside edge of the bell housing. I may not have gotten the npt threads sealed up when I replaced it.... I've worked on ships half of my life as a marine engineer and got the nickname "liquid plumber" because half of what I put together leaks just a little...

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Mopar1973Man

Mopar1973Man

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In my book, RV275 injectors are still basically a stock injector for the Cummins ISB RV engine. The difference is a mere +40 HP (Standard output) or +30 HP (for High Output engine). RV edition of Cummins ISB was a 275 HP engine. Hence the injector name.

 

Back in the day we only had a handful of tuners that could add extra fuel and limited smoke control and no real timing control. This made it hard to build a truck up without smoke. Like myself, I started with stock injectors and the Edge Comp tuner will do very well. Now when I stepped up to RV275 it became smokey just a bit because of lack of timing control and fuel map control basically Edge Comp just adds to the stock maps for only stock injectors Then the +50 HP smoke pretty good. The problem is more you increase the injector size the more you need to advance timing for the larger droplets to convert from liquid to vapor. Hence the smoke problem. Now with Quadzilla Adrenaline, you can control both fuel and timing. I've gone all the way up to +150 HP injectors popped at 320 bar now and no smoke. This is because of the amount of timing I running versus the size of injectors. 

 

 

Edited by Mopar1973Man
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Dumb A

Dumb A

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This is great information for me, thanks again... If I'm understanding correctly a slight bump in HP and possibly a bump in mpg with the RV 275 injectors... That's good enough for me at this point. I've noticed someone installed a Powerpuck on this truck. That as I understand it advances the timing a bit. This may assist the RV275 injectors??? Less or no smoke. As of now I don't notice any black smoke when I'm coming up to speed and seeing boost of 28-30 psi. I may be pulling the head depending on what I find pertaining to the small coolant leak. If I do pull the head it will be going back together with ARP studs....

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