Haven't started the 8V71 for a couple of months, as it has been too cold to do anything here in PA. Was going to take it to get brakes adjusted and an air leak fixed tomorrow, but.....it won't start!
It did start but ran only long enough to suck some of the fuel out of the new spin on filters.
A little history is in order: I was having trouble with the system losing prime, but figured it was my old canister type filters, so I switched over to spin on filters with new bases back in October. I made one run to a campground about 45 minutes away, and all was good.
Today, when I start the engine, it fires right up, but then gets starved for fuel. I pull the primary filter, and yes, it is only half full, so I fill it up right to the top. I check the secondary, and it is down a little too, so I fill it up also. I get back on the starter and it spins over, but won't fire. Previous times when I had this problem, it would start after the filters were filled. I kept trying till I noticed the starter slowing down--which means I knocked down the batteries a bit. The charger is now on the batteries, hoping I can get them up to par so I can try again in the morning.
First I am confused about how it would lose prime, and second why it won't start after filling the filters?
Do I need to use a funnel and fill through one of the ports on the filter base until fuel gets back to the tank? I My fuel gauge tells me that nobody "borrowed" a significant amount of fuel so I don't think fuel is a problem.
Any help is greatly appreciated!
Steve Toomey
PAbusnut
73 GMC 4905A-333
Quote from: pabusnut on March 04, 2011, 05:08:52 PM
. . .A little history is in order: I was having trouble with the system losing prime, but figured it was my old canister type filters, so I switched over to spin on filters with new bases back in October. I made one run to a campground about 45 minutes away, and all was good.
. . .First I am confused about how it would lose prime, and second why it won't start after filling the filters?
Hello PA,
Given the described history I'd bet on a bad check valve or an air leak on the suction side of the system.
Pull the supply line from the primary filter's out port and see if backward flow to the tank is checked, or blocked. Easy, just a little pressure, don't blast it with shop air.
Same pressure testing technique applied before the check valve will possibly hopefully make any air leak noticeable. The supply pump's shaft seal is another potential leak source.
Not immediately starting after simply filling the filters is because the supply circuit to the injectors is still dry.
I'll mention that it takes a while for fuel to soak into filter elements to completely fill a filter for priming. A utility hand-pump that will pull a vacuum makes a very effective system primer. Connection point depends on what's accessible; sometimes a gauge port on top of the filter housing; sometimes the return line, but then you're pulling through the fuel pump, anyway, it still works.
good luck
I had a heck of a time starting mine at first. My filter was full, but the thing obviously was getting no fuel. The line before and after the filter was dry, but the filter full. Strange. Anyway, I finally broke down and put an electric inline pump on the thing. I ran it a few minutes until I had fuel coming out of the line at the filter, reconnected that line, and then ran the electric pump more. I thought that should do it. Nope. Ran the electric pump a while longer. Tried again and finally it took off and ran. Has been ok since. I left the inline electric pump in place in case it ever happens again!
Boyce
I agree with Ted, my check valve failed and the exact same thing happened until I repaired it.
I'm going to install and electric pump just like Boyce in case this ever happens again, probably at a very inconvenient time!
Thanks guys!
I guess I will have to find that check valve and fix replace it just to get it to the shop.
Does anybody know where I can get a small 24VDC inline pump? I just noticed yesterday that my 'New to Me-2006 Jeep Liberty CRD has the little "thumb pump thingy" right on the side of the fuel filter housing. Novel Idea.
I wish I could find one of themanual pumps that were rumored to be on early Macks.
Steve Toomey
pabusnut
Thinking out of the box but some common sense. Why a 24 volt pump? Probably something you may need for 20 seconds a year. Plumb in a common 12 volt pump and jump it with your house batteries.
I guess I didn't think about a 12V pump?! I could basically use a "long extension cord" to get to the batteries in a pinch, or use the toad battery.
PAbusnut
My generator has a electric fuel pump. I carry a spare for it got it at Napa. I have never had a fuel problem yet. But that is probably why, I carry a spare.
You have 12 volts at your starier or gen. A 5 ft. cord and a couple of clips and you are in buss.
Quote from: papatony on March 05, 2011, 03:46:45 AM
You have 12 volts at your starier or gen. A 5 ft. cord and a couple of clips and you are in buss.
I would guess he's probably got 24v if he was asking about 24v pumps.
Plenty of other thing will cause a loss of prime besides the check valve I never had a check valve on my Eagle installed one 65 bucks from DD it still lost prime chased in down it was a hose removed the check valve it's still doing ok as far as I know.
Invest you money in a inline flo/through pump for 70 bucks
good luck
Are all electric pumps flo-thru, seems to me they should be but is a small auto electric pump large enough for a bus flo-thru??
Yes. I've been running my 8V71 on a NAPA 12v fuel pump for 3years and no problems.
Greg, thanks. Do you have it inline or is it set up in parallel?
Guys, I had this one,
http://www.summitracing.com/parts/ATX-E8012S/ (http://www.summitracing.com/parts/ATX-E8012S/)
and put it inline to prime my 8V71. It worked fine for that purpose. It is still in place, but not hooked up. The mechanical pump seems to pull through it just fine, but I have only let the engine run at home..not road worthy yet....
Boyce
Boyce,
Thanks, my concern is the smaller size of my auto pump connections, they are much smaller than the supply line on my bus.
Maybe the one you show has larger tubing, do you know the size?
I'm guessing they have simple rubber flapper check valves and should allow the mechanical engine pump to pull fuel right through.
However, it sure takes a lot more fuel to climb a long grade than to idle. I found that out when I had a small air leak at the gasket of my primary fuel filter!!
Gus
My mechanical pump quit one day. I used an electric pump inline (the type used on automobiles) nothing big and fancy. The bus runs like a dream using just that pump. Maybe this spring I'll fix that mechanical pump.
Greg
The inline electrical pump is a nice backup. My last bus had an electric pump right at the fuel tank and it worked fine. However, I once installed one in an old motorhome I had. I first put it in series, but it did not pass enough fuel to run the engine. I therefore switched it to parallel. I would want to be sure that whatever pump I installed had enough passive flow to let the engine run on the mechanical pump alone.
Put a pump in line, hook up a toggle switch, turn it on and GO. You have nothing to lose.
Greg
I too am concerned about the smaller fuel line diameter/flow rate. That is why I pointed out I haven't been on the road with it yet. The lines on the auto pump are 5/16 if memory serves. I had to adapt it to the bus line which I believe is 1/2" I have not been running the electric pump since I got the detroit running. I have been just letting it pull through the electric pump. Seems OK so far.
Boyce
5/16 works good you guys as my dad said put the thinking hat on fuel is pumped up and goes out a 0.070 hole on the return line I use the rotary type pump not a impulse cheapo has worked good over the years for me
Clifford, I am not sure I understand what you are saying. .70 inches would be almost 3/4 inch while 5/16 is just more than a quarter. Do these pumps give their passive flow through rates?
Check it now Lin 0.375 would have been 3/4 I left off a zero in the first post
If you say it will work Clifford, I'm sure it will, but .375 is 3/8" which is still larger than 5/16".
I knew that just wanted to keep you on your toes 0.750 is 3/4 I love you guys looking for mistakes I really do
good luck
Fortunately, we don't have to look very far :D
Hey Clifford, I am not looking for mistakes. I am trying to understand what will work. I am looking to avoid mistakes.
Lin,
Was your MH pump near the tank?
Greg,
I really like the idea of the electric pump as a backup to the mechanical pump.
Cliff,
Fortunately I paid attention in school during decimals so you don't keep me on my toes, but you do keep me guessing!!
I'm sort of interested in the flow volume of the mentioned large Auto Zone pump because I always plumb off road equipment with a complicated bypass system and flow-through would make for cleaner and simpler installations.
The crucial data would be knowing the flow volume of the DD fuel pump.
I wonder if the overhaul manual has that spec? I could check sometime.
We know that a 318 can burn a gallon of fuel in three minutes on a hard pull. So the question is how much more flow than .33gpm is needed to assure adequate supply and cooling?
---
0.9 gmp fuel spill on a 6v or 8v92 engine Ted fwiw
good luck
Gus- the electric fuel pump on the bus was right by the fuel tank. The one I installed on the 440 motorhome was by he engine. I ended up putting it in parallel and adding, I think, two check valves.
When the bus is cold, or has been sitting for a while, I turn on the electric pump, let it run for 3-5 min. and the beast always fires up immediately. That's the way I roll--lol
Greg
Thanks guys!
I'll be ordering the check valve tomorrow. I did get it started last saturday and ran it up to Paul's Garage in York Springs to get the brakes adjusted and (now) 2 air bags replaced. I think I found where the check valve is on the bulkhead ahead of the engine.
When I find a 24Vdc pump, I will put that on in a bypass loop for re-priming.
Steve Toomey
PAbusnut
maybe you should look into a dropping resistor and use a 12 volt pump. Airplane guys use a dropping resistor to use 12v things in there 24v(28v) aircraft. You could try Aircraft Spruce for instance.
Lin,
Suction pumps don't work well unless they are close to the tank, probably the reason the Dodge pump didn't work so well. I can see why such a small pump won't pull enough suction on such a long fuel line.
PA,
Two weeks ago my 8V71 wouldn't start after three long attempts in 72* weather. First time it ever failed to start even in 10* weather since I bought it in Dec.
Today at 65* it started on the first crank.
I finally decided that two weeks ago my batteries were not fully charged. Today they had been charging for a week on my newly installed converter with a four-stage smart charger. My conclusion is that those 8Vs like to spin to start and weak batteries won't do it.
Gus,
The electric fuel pump worked fine on that Dodge 440 if it was turned on, but it did not let enough fuel pass if it was off. I would like to add an electric pump inline in the bus. It would be great for priming if needed and also as a backup should the mechanical pump fail. I just don't know which one will definitely allow enough fuel to pass when it is turned off. I suppose that one could just leave the pump on all the time, but I prefer not to. It sounds like Clifford has one that works, so it must be doable.
Busnuts usually report plumbing an electric priming pump in parallel to the main fuel line, using valves or check valves to put them in or out of play.
That takes the flow-through consideration right out of the thought process, and opens up the opportunity to use less expensive/smaller components.
happy coaching!
buswarrior
Obviously a pump in parallel has no flow through problem but it is so much easier to plumb in series where all those elbows and valves are eliminated.
I want to install one but want to go the simpler series route.
Lin, Clifford use to leave his on if I am not mistaken, I have the same as Clifford's, I leave mine off till needed for filter changes, this June will make four years/ 2200 mi, no problem o Amigo! I think mine was from Car Quest 63 bucs, In-line/Diesel rated/flo-thru/ built in check valve. It has been more than adequate and keeps my 9G90's smilin' ;D
Van,
Sounds good to me. I don't suppose you have the part number or know what size tubing it uses?