thancoc@bellsouth.net Posted October 26, 2022 Share Posted October 26, 2022 Hey guys, i am in a bind could use some guidance. I am currently at Topsail State Park (we are volunteers) been parked for 4 months. Went to fire up the coach and it started then started sputtering and coughing and then died. Tried it a couple more times and is sound like it was a fuel issue. So, I changed out the filters and the engine did the same exact thing. The fuel tank was fuel when I parked it with Diesel Kleen as treatment and the fuel that was poured out of old filters look great! Up on further review my lift pump is leaking. I called my back home mechanic and he walked me through a couple things! I took the pressure side fuel filter off and turned the key on and got no fuel from lift pump! When I screwed it back on and then unscrewed I had air pressure because it spit out a little fuel! So I have two questions: One does anyone have any thoughts as to what is going oncan a leaking or faulty lift pump cause this? Second, does anyone have any suggestions for local diesel mechanic between Ft Walton Beach and Panama City, Fl Topsail State park is right in the middle of the the two in Destin FL. Help supposed to be out of here by Monday! Link to comment Share on other sites More sharing options...
OhReally Posted October 26, 2022 Share Posted October 26, 2022 I can help with your first question. The lift pump relies on sucking fuel from the fuel tank to the pump. After it runs for a short time it will quit and your mechanical fuel pump on the engine takes over. Because of the location of either pump they need a hose from the tank without leaks. If there are any leaks between the lift pump and the tank you will get something like you describe. The easiest way to find the leak is to apply air pressure to the line, either at the intake to the lift pump or the outlet from the tank, and then inspect the rest of the line for leaks. Not an easy task. Good luck. -Jamie Link to comment Share on other sites More sharing options...
thancoc@bellsouth.net Posted October 26, 2022 Author Share Posted October 26, 2022 I am pretty sure it is leaking from the pump housing where the gasket is. going to try to tighten the three bolts in am to see if that helps but was really wondering if the leaking of fuel would be enough for fuel not to flow. its dripping not pouring Link to comment Share on other sites More sharing options...
OhReally Posted October 26, 2022 Share Posted October 26, 2022 Yes, if lift pump is leaking, your mechanical pump will lose it's prime through the leaking lift pump. I had similar problem with leaking lift pump a couple years back and tightened bolts fixed it. Fwiw I have heard that low sulfur fuel will attack some gaskets so your (our) bolt tightening fix may only be temporary. -Jamie Link to comment Share on other sites More sharing options...
Cubflyer Posted October 26, 2022 Share Posted October 26, 2022 Once you tighten the three bolts, loosen the filter just down stream of the lift pump, before the injector pump. Get a rag, wrap it around an air nozzle, and blow air into the filler neck of your fuel tank, watch for fuel to leak from the loose filter, tighten that filter and keeping the air pressure on the tank, start the engine.... Link to comment Share on other sites More sharing options...
thancoc@bellsouth.net Posted October 26, 2022 Author Share Posted October 26, 2022 Question, the leak at the lift pump can cause the Lift pump not to prime right. Becasue is the three bolts dont stop the fuel leak I am going to have to replace the gasket on the pump, which I will have to drop the starter?? ugghhh and if the leak stops I then do as you suggested-So, the that is the filter under pressure from the lift pump and then make like a seal at the tank to blow air into will there be enough force to flush out the air in system?. Link to comment Share on other sites More sharing options...
jacwjames Posted October 27, 2022 Share Posted October 27, 2022 If you can tighten the bolts it may stop the leak. If you have a replacement gasket you should be able to replace from above. If you can't get the lift pump to fill the filters and push fuel to the injection pump air pressure may help. But make sure the lift pump is not leaking and/or sucking air with the engine running. If the injection pump sucks air it could damage it. Link to comment Share on other sites More sharing options...
Robert U Posted October 27, 2022 Share Posted October 27, 2022 I have had a leak from the lift pump before and it never caused a problem about starting. I tightened the 3 bolts to keep the leak from making a mess. The lift pump only runs for about 30 seconds. Try turning ignition on and listening if pump is running. You can hear it in the back. After 30 seconds turn off switch and then back on again.after doing this for 3 or 4 times try starting engine. If you have changed filters make sure they are not leaking as this will cause your problem. Starting the engine about once a month is a good idea. Bob U 2000 Dip Link to comment Share on other sites More sharing options...
jacwjames Posted October 27, 2022 Share Posted October 27, 2022 The leak while the pump is running isn't the real problem. The problem is when the transfer pump stops pumping and the injector pump starts sucking fuel all the way from the tank and will then start sucking air. The air in the system is the problem, it will eventually cause the injector pump to fail. ~$5000 problem 1 Link to comment Share on other sites More sharing options...
thancoc@bellsouth.net Posted October 27, 2022 Author Share Posted October 27, 2022 The fuel filters are not leaking! The lift pump does actuate for about 30-45 seconds. I took the pressure side fuel filter off and turned on the pump and it did not pump fuel, not sure if it would. But as soon as the pump turns off a back flow of fuel comes out. I had the gasket replaced about 6 years ago and it has a pretty good size drip. I have sprayed some WD40 on the three bolts and will attempt to tighten them in the am. I am praying this stops the fuel leak and maybe keeps any air out so it will prime and run. There are no other leaks and the RV ran 1000 miles like a charm before I shut it off here in Destin. I will be praying hard tonight for the three bolts as the Lord knows I will not sleep! I do not have enough time at this point to install the FASS system. as we have plans for the next two weeks with a Turkey day trio to TX. If I replace the lift pump it appears I will have to drop the starter to access the pump. Thoughts Link to comment Share on other sites More sharing options...
Cubflyer Posted October 27, 2022 Share Posted October 27, 2022 Those three bolts I believe are metric..... 6mm or 8mm... I'm old and tightened mine almost two years ago.... I'm not sure of the size, but 1/4" drive 18" extension with swivel socket or u-joint will help. If your lift pump is running, but no fuel is being pumped, it most likely lost it's prime, the gasket that leaks and drips down on the starter usually leaks with lift pump ops and no engine start (like when you just cycle the ignition key but do not engage the starter, that's how I found out mine was leaking). That gasket leaking allows the injector pump to draw air when the engine is running and the (30 sec) lift pump is not running. Sounds like you need to put that air pressure on the fuel tank to force fuel to the lift pump.... to get the engine to start/run. Get it running and find out why it lost it's prime later... Link to comment Share on other sites More sharing options...
thancoc@bellsouth.net Posted October 27, 2022 Author Share Posted October 27, 2022 Cubflyer that is my plan for the am. I will have to go get a swivel socket. is there a cap I can buy for the fuel tank pressure? Will a rag do the trick? Link to comment Share on other sites More sharing options...
Cubflyer Posted October 27, 2022 Share Posted October 27, 2022 3 minutes ago, thancoc@bellsouth.net said: is there a cap I can buy for the fuel tank pressure? Will a rag do the trick? You might try blowing air into the tank by way of the vent also, not sure if that will work due to the rollover check valve, but it should... try there first, then if not a rag wrapped tight should work. I believe the fuel cap is just a 2" (or so) pipe thread, so you could get a plumbing cap (rubber?) and put a small hole in it.... be careful to not put too much pressure on the tank... it should only need a couple of psi.... Ken Link to comment Share on other sites More sharing options...
thancoc@bellsouth.net Posted October 27, 2022 Author Share Posted October 27, 2022 understood Link to comment Share on other sites More sharing options...
Hypoxia Posted October 27, 2022 Share Posted October 27, 2022 It's been a while since I changed an ISC lift pump. I thought the lift pump fed directly into the injector pump and all filtering was prior to the lift pump. You can test the lift pump pressure on top of the pump, there is a plug which you remove which is metric. I have a metric straight thread (10mm-1.00 I think) to 1/8" NPT adapter I use so I can put a pressure gauge on it. I also believe the pressure should be 10 PSI at the pump. I also thought the lift pump had to be removed to get access to the screws that tighten the gasket. I have a spare ISX lift pump, I'll have to look at it to refresh my memory. Lift pumps can leak from the gasket or through the electric wiring hole. Cummins Quickserve will have the procedure for testing the pump. Adapter kit metric to NPT. Equus Adapter Kit Link to comment Share on other sites More sharing options...
Hypoxia Posted October 27, 2022 Share Posted October 27, 2022 Here are lift pump photos Link to comment Share on other sites More sharing options...
Cubflyer Posted October 27, 2022 Share Posted October 27, 2022 (edited) 2 hours ago, Hypoxia said: It's been a while since I changed an ISC lift pump. I thought the lift pump fed directly into the injector pump and all filtering was prior to the lift pump. Jim C It would appear that your photos are of an ISX lift pump since it does not look like the ISC pump on my 2003 8.3. I am sure that on my 2003 8.3 ISC engine the output of the factory, engine mounted lift pump feeds directly (through a rigid metal tube) to a spin-on filter before continuing on to the injector pump. The mounting bolts (three) are long and install from the top down through the housing body and screw into the lift pump... From your photos the ISX lift pump seems to mount differently... Ken Edited October 27, 2022 by Cubflyer clarity Link to comment Share on other sites More sharing options...
thancoc@bellsouth.net Posted October 27, 2022 Author Share Posted October 27, 2022 any tricks on how to lossen or tighten? Link to comment Share on other sites More sharing options...
timaz996 Posted October 27, 2022 Share Posted October 27, 2022 From Jim "The leak while the pump is running isn't the real problem. The problem is when the transfer pump stops pumping and the injector pump starts sucking fuel all the way from the tank and will then start sucking air. The air in the system is the problem, it will eventually cause the injector pump to fail. ~$5000 problem" Mine ending up costing $6500 because I was stuck on the side of the road and had a mobile mechanic replace it with a factory rebuilt pump. A new pump was $6500 just for the pump. I had planned on putting in the FASS system before it happened and didn't have a leak on my lift pump. Just a thought to make the FASS more of a priority. I bought my coach in 2017 so I have no idea if there was a leak before. 1 Link to comment Share on other sites More sharing options...
Cubflyer Posted October 27, 2022 Share Posted October 27, 2022 29 minutes ago, Tim-AZ said: ......... didn't have a leak on my lift pump. Just a thought to make the FASS more of a priority. I bought my coach in 2017 so I have no idea if there was a leak before. When I first got my coach, it had a leaking gasket at the lift pump...... BUT, I did not know it.... I only discovered it when I was t/s a ABS light problem. I was turning the key on and off a number of times without starting the engine..... pretty soon I noticed a puddle of fuel under the engine, dripping from the starter... I 'lucked out' and promptly bypassed that pump and installed a FASS system. Best thing I ever did for my engine, and gained the knowledge that the injector pump always has a positive pressure of clean air-free fuel to it's inlet (from the FASS) with a fuel pressure gauge installation. Ken Link to comment Share on other sites More sharing options...
thancoc@bellsouth.net Posted October 28, 2022 Author Share Posted October 28, 2022 I have got a new gasket going to be here tomorrow I am going to install and pray that it starts. I am heading to Atlanta where I have a solid mechanic, who will install my fass system hopefully in next two weeks. thats the current plan. I will keep you posted. 1 Link to comment Share on other sites More sharing options...
Cubflyer Posted October 28, 2022 Share Posted October 28, 2022 On 10/26/2022 at 5:56 PM, thancoc@bellsouth.net said: Up on further review my lift pump is leaking. This problem started with a -no start-, the first thing you did was replace the fuel filters, (inducing a bunch of air into the fuel supply system), then you had a fuel leak at the lift pump, still no start, now you are going to change a lift pump gasket and hope it starts.... What is your game plan if 1- you can not change the gasket (wrong gasket or since that gasket change is a bit of a PITA) 2- you get the gasket changed and still no start? If it were me, I would concentrate on getting the engine running (seems fuel to the injector pump IS the problem), by forcing fuel through those new filters and to the lift pump and on the the injector pump...... many an engine would not start after fuel filter changes as pumps can not pump air very well, you need to prime the pumps! Once running, determine if the lift pump is leaking a little or a lot. I drove mine (unknowingly) from south FL to Memphis, where I realized that the drip of liquid (fuel) hanging off the starter was a sign of a leaking lift pump. Best of luck, Ken Link to comment Share on other sites More sharing options...
jacwjames Posted October 28, 2022 Share Posted October 28, 2022 There are two styles of gasket depending on which lift pump you have, hope you ordered the right one. If you get the lift pump gasket replaced I'd remove the fuel filters and fill with clean diesel, plug the inner hole. The cycle the key 5-6 times. If they rig doesn't start then you have a different problem, all likelihood the injector pump itself. Do you have anyway of getting fault codes????? Link to comment Share on other sites More sharing options...
thancoc@bellsouth.net Posted October 28, 2022 Author Share Posted October 28, 2022 Words of wisdom and thoughts Cub- Thank You. I can tell you when you have breakdown issues. this site and IRV2 sites are like having friends standing around trying to help! Make a nervous fellow feel good!! I have laid in bed the last two night trying to put together a plan. I have got a new gasket going to be here tomorrow, found the exact gasket for pump I have already had my hands on the lift pump cleaning it and trying to stop the leak. The bolts have been backed off and tighten so It will be fairly easy to take off.. My plan is to do that tomorrow when the gasket arrives. I am hoping to do the air purge like you guys suggested from the tank and loosen the filter in the back while running the lift pump? I have a mechanic scheduled to be here Monday whose is familiar with my engine and lift pump. I have also copied and pasted the CAPPS Fuel pump link on EBAY if I have REAL Issues. I am heading to Atlanta where I have a solid mechanic, who will install either FASS or AIRDOG hopefully in next two weeks. thats the current plan. I will keep you posted through the process. Link to comment Share on other sites More sharing options...
thancoc@bellsouth.net Posted October 28, 2022 Author Share Posted October 28, 2022 13 minutes ago, jacwjames said: There are two styles of gasket depending on which lift pump you have, hope you ordered the right one. If you get the lift pump gasket replaced I'd remove the fuel filters and fill with clean diesel, plug the inner hole. The cycle the key 5-6 times. If they rig doesn't start then you have a different problem, all likelihood the injector pump itself. Do you have anyway of getting fault codes????? My Engine serial number required the original type gasket 4928511. found a guy out of TX on Ebay to send me one. I found a diagram of both the old gasket and the new gasket (4928512) in a IRV2 feed. I am thinking since it was running like a champ when I shut it down that the CAPPS pump is still ok? I truly think since I sat here for 3 months that the leak may have allowed air to seep into system and allowed the fuel feeding the pump to drain back in the tank. Thats what I am hoping. I have learned more in three days about the fuel system than I cared too. But I am guessing, so I am trusting the mechanic I have coming this way will have a scanner. Plus it will be money well spent. if he gets me going and teachings me a few tricks as well. Breakdowns are no fun, but at least I am in a volunteer spot here at the park and not on side of road! God is Good!! 1 Link to comment Share on other sites More sharing options...
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