Fuel filters changeout issue

[Mat7783]

So a follow up to my bus losing power on initial ride home last week.we think it was bad fuel so I changed out the fuel water separator and secondary fuel filter as shown. You can see the nasty filters removed with rust.i filled the filters as recommended and a new air filter. She started right up and idled just fine but when I put it in gear, it stalled and now she turns over but won’t start again. I purged the new seperator and clean fuel come out so I am puzzled. Any ideas would be greater appreciated.

 

[Brad_SwiftFur]

Sometimes you need to really rev up the motor after a fuel filter change (hold the throttle for a few seconds) to make sure all the air is purged from the system. The engine may run rough/skip a bit as it purges the air, but once it smooths out, you should be good to go as far as purging the air out of the fuel system goes. I've seen quite a few shops and mechanics do this.

 

[Native-SKO]

I was thinking much the same, especially if you filled the filters with fuel and not the priming pump. I was thinking you may have been running on the fuel you put in the filters and not by drawing from the tank. I may be wrong here, but it seems that way to me.

 

[Truthseeker4449]

My bus did this too. My solution was to turn the key on, then key off after about 10 seconds. If the bus has an electric fuel pump, this will help prime the system. Repeat this a couple of times, then crank the engine for up to 20 seconds. Then wait at least 2 minutes for the starter to cool and repeat from the beginning until she runs. IIRC I had mine running after about 15 minutes, though I wasn't being a good boy about letting my starter cool as much as I should have.

 

[Booyah45828]

Well, it's a good thing you changed the filters, those ones are trashed.

I filled the filters as recommended

Who recommended that to you?

I'd say you sucked air and need to pump the primer pump more to get it out. It's likely just a coincidence it stalled when you put it in gear.

 

[EastCoastCB]

Well, it's a good thing you changed the filters, those ones are trashed.



Who recommended that to you?

I'd say you sucked air and need to pump the primer pump more to get it out. It's likely just a coincidence it stalled when you put it in gear.

You can prefill them if you do it the right way, plugging the center and using filtered fuel.

 

[mmoore6856]

You can prefill them if you do it the right way, plugging the center and using filtered fuel.

i have pumped that primer sometimes over 1000 [yes thousand] times to prime a cat like this. if you make sure you are using clean fuel from a clean container you can fill them as east recommended. sometimes you must bleed air out of the lines while pumping it. i have never seen a electric pump on a cat engine either. i once saw a guy use a shop vac on a bleeder port prime a engine that was a allison air cooled diesel he put in a truck. [former airplane engine] it worked to prime it

 

[mmoore6856]

yes i tried to fill the filters with the primer pump, but only once . ill always fill them with clean and be as quick as possible changing them

 

[EastCoastCB]

i have pumped that primer sometimes over 1000 [yes thousand] times to prime a cat like this. if you make sure you are using clean fuel from a clean container you can fill them as east recommended. sometimes you must bleed air out of the lines while pumping it. i have never seen a electric pump on a cat engine either. i once saw a guy use a shop vac on a bleeder port prime a engine that was a allison air cooled diesel he put in a truck. [former airplane engine] it worked to prime it

I changed mine using the directions I gave the op. Was easy as pie. Didn't have to do anything. Just started right up and runs like new.

 

[Mat7783]

Follow up on fuel filters:

So I pump this priming pump handle after first filling my new filters and I got resistance. Now after the bus idled and then stalled in gear,this pump will not give me resistance after hundreds of pumps. Need to get a filter wrench to take off fuel filter to see if it is empty. If so, should I replace the pump handle asst?it may be bad and not priming filter??

 

[Booyah45828]

You can prefill them if you do it the right way, plugging the center and using filtered fuel.

Yeah, I know that.

I was just curious who recommended it to him.

Most oem's advise against it. So the only reason I would ever do it is if there isn't an electric lift pump or primer pump, which he has.

It helps with the primer pump if you bleed the air while doing it, otherwise you have to push the air through the mechanical lift pump, which sometimes doesn't happen.

Typically there is a bleeder of some sort on the filter, whether it's a schraeder valve, or a plug with an o-ring on it.

Even cracking the line loose before the lift pump to bleed air can suffice.

 

[mmoore6856]

I changed mine using the directions I gave the op. Was easy as pie. Didn't have to do anything. Just started right up and runs like new.

yes thats what i and all the cat owners i know do. lots of suggestions here that evidently never seen a cat engine

 

[mmoore6856]

i figure using clean fuel and prefilling them is cheaper than burning up a starter or wasting batteries

 

[Mat7783]

HELP!! I am still struggling with my fuel issue. Took off new fuel filter today, refilled it with fresh fuel, installed it and the bus started again. I revved it a little and started to idle nice. Put in drive and reverse like 3 times and then she stalled. Fuel filter out of fuel.i primed pump handle for 5 minutes and not getting to a resistance.Is there anyone near to Sanford FL that can come by and give me a hand getting this going again. It started perfectly on drive home prior to changing filters.i will reimburse gas money and pay you a fair sum to help me and show me a few things on this bus??

 

[EastCoastCB]

maybe the transfer pump has failed. From the pic of your old filters it looks like you had/have a good bit of water in the fuel system.

 

[Mat7783]

Yep. The water seperator filter was empty when removed. Looks like rust in them. Not good. Where is the transfer pump? I am super green with this bus��

 

[Mat7783]

Ok. I found the transfer pump. Do I have be concerned with high pressures or anything other than changing out this pump?? I see a kit with O rings and such.

 

[EastCoastCB]

Nah. The high pressure fun starts at the hpop.
I've never messed with mine yet, so do some google-fu and there will be some rv owner's write up of how to replace it. Can't be too bad but who knows.
I'd check your lines for blockage too. Could be algae or something blocking the flow of fuel.
If its this bad I'd take a look at the inside of the fuel tank for rust of grime. If the fuel is really old or real watery you'll want to get that out and some fresh fuel in.
Also don't be surprised if your filters are needing replacement again as any gunk in the system will end up in them.

 

[banman]

Yep. The water seperator filter was empty when removed. Looks like rust in them. Not good. Where is the transfer pump? I am super green with this bus��

Ok. I found the transfer pump. Do I have be concerned with high pressures or anything other than changing out this pump?? I see a kit with O rings and such.

How long was the bus sitting before you bought it?

Do you have more than a ¼ tank of fuel?

Open the drain plug on the bottom of the tank -- I let about 4gal flush out of mine to ensure any water and dirt on the bottom of the tank came out.

Pour some of that fuel in a glass jar and let it settle -- then gently swirl it. I could easily see water droplets drifting around when I did this with mine.
If the fuel coming out doesn't look and smell like fuel, drain it out till it does...

I'd refill both filters and BE PATIENT this time after you start it. Just let it run at high idle for ten minutes or so BEFORE trying to put it in gear. Give it time to pull a solid stream of fuel from the tank to the engine before you put the demand of open throttle on it.

The tech at my local Freightliner dealer said it usually took an hour to reprime one of these engines after a filter change -- priming the pump and blipping the starter motor for 20 seconds... CAT says not to pre-fill the filter... CAT is more concerned with getting contamination in the filter (from pre-filling) than how long it takes you to prime...
By pre-filling my filter my 3126 started in seconds -- too easy.

I stroked my primer hundreds of times and never felt any resistance -- I suspect they air/vapor lock. Maybe you're supposed to crack open the fuel fitting downstream of the primer pump?

 

[EastCoastCB]

How long was this bus sitting?
I've had some buses sit for a couple years and not get that bad.

I'm curious about where the bus is from.