454 Engine feels like its running out of gas

Rickf1985 · July 17, 2016, 07:07 PM

If you have 12 volts with no load and 9 volts when turned on then it is not a pump problem it is an electrical supply problem. You have a major voltage drop somewhere in that line. What size wire are you using? Should be no smaller than 14 gauge at bare minimum. Could be a bad connection at the source of the wire also or it could be an overload since it is also powering the choke coil. You have the very same pattern no matter what you have tried with fuel pumps and it all sounds like the tank is going into vacuum. Have you put a NEW VENTED gas cap on there? I know you said you loosened the cap and it ran great for quite a while and then did the same thing. It is possible the cap ran itself in enough to seal as you drove. Try a vented cap. they are only ten or fifteen bucks. Or would have been down here anyway.

On edit, If the choke coil is only triggering th relay then that will not cause a voltage drop, check the power from the hot wire at the source through the relay to the pump.

cook elandan · July 21, 2016, 09:25 PM

OK, you are trying to fight or find the issue that you have. Start simple. Does you MH run on the AUX tank correctly? Like I stated before, start simple and then you can work on one thing at a time. You are stating that you have an in-tank pump. Is it still in the tank? Does it work? You say you put on a new fuel regulator. Is it adjust correctly? You said you have a new selector valve, but you stated you by-passed it. Is it hooked backed up correctly and is it operating correctly?
I ask this because you are now stating that you have another fuel pump in the system. You are adding more into the mix making it little harder for you to trouble shoot. You need to find out if you are getting flow from the rear tank. Set the selector valve for the rear tank. unhook the fuel line from the block fuel pump and see if you are getting the correct flow into a container. If you are trying to draw fuel through the in-tank pump, even though it should, it might not. There might be a chance that the fuel line in the tank on the pump may be bad.

BrianB · July 22, 2016, 01:11 AM

I realize that a lot of this is disjointed and hard to follow, but if you read through all the replies, the info really is there.

1. Behaves the same when running on either tank. I know for fact that the valve is switching correctly and is not a contributor to this problem. Verified by running on each tank separate occasions and looking at which tank needed fuel to top off.

2. In tank pump in main tank is still there, not operational, so has to pull through it. No pump in aux tank. This is not an issue due to observations related to #1 above.

3. Bypassing the selector valve was 2 weeks ago when trying to diagnose the issue. It's been hooked up normally since Edmonton about 2 weeks ago.

4. The mechanical pump on the engine is working as the engine ran when the electric pump died, just couldn't keep up.

5. The external electric pump was added in Edmonton to try to solve the problem.

6. I have moved that pump to the back of the coach, mounted right above the selector valve. Inlet connected to the output of the selector valve, outlet connected to the 1/2" line that runs up front.

7. I just rewired it with 12 gauge wire to a relay at the front firewall. With the engine running (to establish oil pressure and engage the relay) the pump I have on there is pulsing.

8. I made a statement about the voltage at the pump only being 9 volts. With a good pump, running, it was really about 13.6 volts at the pump, 14.0 volts at the relay. So I think that 9 volt reading was due to a fried pump pulling excessive current. It's not the normal case and I doubt had anything to do with the pump failing.

So, where am I on this issue? I rewired the pump with 12 AWG wire. I replaced both as caps with new vented ones. I made it about 14 miles down the road and the alternator seized up. So I don't know for sure yet. Hope to be back on the road tomorrow when the new alternator arrives (that's a whole separate topic really).

Attached is a diagram of my current setup.

cook elandan · July 22, 2016, 05:10 PM

So, I looked over your posts, how long have you had your RV and have you driven it before you started having all the issues with the fuel. Sorry, I didn't know that your AUX tank is all the way in the back of your unit. In my 85 Elandan 34', my main tank is in the rear and the AUX tank is just in front of the rear tires. Still, the RV has 113k miles on it and I have all the paperwork and driving journal. It list every thing and mileage of when the PO had anything done. It doesn't have a electric fuel pump, just the mechanical pump on the block. The most that was done was they had replaced the clutch fan 5 times. So we know that for the most part the the unit run without an electric fuel pump, also by way that your unit doesn't have one in your AUX tank and it is further back. I would still say to start there, get your unit running on the AUX tank with no issues and then I would replace the in-tank pump. get your unit set back up to factory and you should be set. Looking at the way that the electric pumps are set up, is your oil pressure high enough to keep the pumps running or is the pressure switch working correctly.

BrianB · July 23, 2016, 12:42 AM

Got the alternator replaced today and headed south towards Anchorage.

Fuel issue is not resolved, though it is cold and raining so that helps. I don't know if the colder air is helping fuel economy and that's why it's not so bad as when the air temp is warmer.

It was mostly just on a couple of uphill slopes. I did stop at top of one where the problem was and got underneath... the pump was chugging away.

At this point I wonder if it's just the size of fittings restricting flow. It's an SP8016 pump (http://ecat.spectrapremium.com/prod/SP8016) with 1/8 NPT threaded connections. I have nipples in each going to 3/8 (inlet) and 1/2 (outlet) hose barbs into the rubber lines.

I will be in Anchorage in the morning so at least the choices for parts stores and parts availability will be better.

Rickf1985 · July 23, 2016, 11:47 AM

I can tell you one of the problems could be the location of the electric pump, it will not want too pull through filters and valves but since it also has the mechanical pump pulling with it that should not be an issue as long as the mechanical pump is working correctly.

Looking at the specs on the pump it shows 21 GPH, that is going to be pushing it on a hard pull up a mountain. 21 GPH is 1/3 of a gallon per minute. That is 43 2/3 Oz.s per minute. At WOT you are going to easily use more than that. I am using the lower end of the GPH scale since you are pulling through a filter and a valve which is going to put a hurting on a pump that is designed to be in the tank. Still, I think that with TWO pumps you should be able to pull it off, the fitting size may be a problem but there is not much you can do about it since the smallest fittings are the ones on the pump. You need a bare minimum of 3/8 opening all the way from tank to front pump and at least 5/16 to the carb if not 3/8.

Ike · July 23, 2016, 02:49 PM

My question for you would be when that shop looked at it did they check the carburetor. Mine did something similar to yours as you stated in original post and I found a carburetor guy to look at it. He found out by looking down the throat of the carb with it running that it wasn't getting as he put it enough squirt. So he took it apart ,new accelerator pump also metering rods fell out of air horn which he says is common on older carbs. He rebuild it to get us back home and it ran great after that. This was after new fuel filters new fuel pump new wires ,new cap and rotor. All these items may have helped but it was the carb the whole time getting progressively worse.

BrianB · July 23, 2016, 03:00 PM

Ike,

Reasonable question. The mechanic did tune it up some - fixed the choke, adjusted the high and low idle.

I do know that it does run out of gas in the carb and I've had to either use starting fluid or dump gas into the float vent to get it going again. That is still suggesting a delivery issue.

Rick,

I think that may be my next option - bypass the filters and see if that helps. If it does, I'll put the one back in just ahead of the mech pump on the side of the frame. I still have spare filters (both frame rail one and carb one).

If not, I'll look and see if I can find a pump with bigger fittings.

I do still have to get back to NY in a couple weeks.

Ike · July 23, 2016, 03:35 PM

Also just for info when my carb was apart it had a bunch of charcoal in it, a new canister was put on along with a fuel filter on the vacuum hose going to the carb.

cook elandan · July 24, 2016, 07:47 PM

Brian, another path that you could go would to get a high pressure pump and install in between the main tank and the pressure regulator. It would be more back to factory spec other than having to pull through the in-tank pump.

BrianB · July 24, 2016, 11:22 PM

Cook,

All that fuel line is inside the frame rail by the tank. Would hae to drop the tank to get to that. Not happening until I get back home.

So, I did as Rick suggested and bypassed the filter on the aux tank between the tank and valve with a piece of 3/8 fuel line I had on Sat morning. Ran fine on aux all way to Anchorage. I filled up there and drove out to Kenai River. There was a 4 mile long 5% or so uphill grade that it made pretty much just fine.

Going to find a piece of 1/2" line to bypass main tank filter before we leave Homer And see how it behaves on main tank.

Cautiously optimistic but not ready to declare victory just yet.

cook elandan · July 25, 2016, 10:08 AM

Cool, glad to see that you are running better. Like I stated back in post 13 and 28, would be best to start with simple and then work out through the bugs. What you have went through will only help improve things for the rest of us. As for me, when i drop my main tank, I will be putting in an access point to by-pass it should the same issue come my way. I am more looking to installing an external pump instead of the in-tank pump. I know that I could mark my floor and cut in an access port to get to the top of the tank like some have but I think that my water tank is mounted over top of where it would fall. You have a safe rest of your trip and I have enjoyed your link for the placed you have been. Thanks.

Rickf1985 · July 25, 2016, 11:58 AM

As you said you are going to make up the one to bypass the filter, I agree with that idea as long as there is one filter between the pump and the carb. I don't know what filters you have in there now but since you are "supposed" to have a filter before a gear drive electric pump I would use nothing more than a common inline clear plastic filter. They filter quite well, they are not restrictive and they are cheap. Run for a while as you are to verify the filters you had were the problem then put one of these in and see if the issue comes back, it should not. Here is a suggestion, Make this up ahead of time so if you have a problem you have it on hand ready to go.Make up a hose at least 3/8" t0o be able to bypass the electric fuel pump and all of the restrictive fittings associated with it. If you have problems again and determine it is not the filter then try that, the mechanical pump is more than capable of pulling the fuel from the tanks so that will not be an issue and this is not a vapor lock problem you are having so this will not change anything there. I think you may be starving the front pump due to those very small pump inlet/outlet fittings. The setup I would like to see is the engine pump and an inline filter between that and the carburetor. That is the ideal setup. If you are using an electric on the line then a prefilter is usually required to protect the pump warranty, I do not agree with pre filters since they restrict an already low suction pressure.

crd · August 21, 2016, 12:49 PM

BrainB I see you made it back to NY. How did the rest of your trip go? Did you resolve your running out gas issue? I am making the same trip next year in our 89 chieftain and have been following your post. Any advice?

kansascat · August 24, 2016, 11:35 PM

Im fighting almost identicle issues with my 79 P30 cruz air. Ive actually got a elec in line pump mounted near both tanks ran off relays that switch them on and off with the fuel selector valve, plus a HD elec in line pump after the fuel selector valve, plus a second new mechanicle pump. rerouted the fuel line out thru the wheel well area and tp the carb for less heat and removed all but one in line filter and it still starves for fuell to the point of quiting when its hot out. When it wits i can remove air cleaner and see fuel boiling in carb. Exhaust flapper is open but that stupic cross over heat in the intake i think is killing me. When its cold out its not nearly as much a problem as when its above 90 out. Much worse if i have to slow down or god forbid stop at a light as that causes it to boil again. All new hoses. tanks cleaned. Im thinking the fuel lines running down the frame rails near the exhaust pipe might be causing the gas to heat to the point of near vapor lock. We fought it all 3 weeks we were out this summer. My plan now is to replace the intake and carb with after market ones without the heat cross over port. Have to try and figure out what manifold to go with for Rv use, and am thining edelbrock carb, and while it apart might as well put in a better cam since 79 was emissioned to death and before they had a clue what they were doing. Anyone here have suggestions on intakes and cams?
Really would like to hear how the return trip went tho on this thread and what solved the problem finally.

Rickf1985 · August 25, 2016, 12:33 PM

Edelbrock Performer Plus package. You get the cam, intake and carb. Plus all the extras like cam lube and valve springs if they are needed. I don't think they are for that cam. The great thing about this kit is that it is a tested and proven setup that is designed to work together. You will get a better bottom end grunt and better midrange. Make sure you order a kit for no EGR to eliminate the crossover.
With the setup you have now are you using an isolator gasket under the carb or just a thin fiber gasket? You should have a insulator gasket that is about a 3/8" thick with spacers in the holes.

kansascat · August 26, 2016, 10:19 AM

So far my initial searches for the performer plus package to fit a 79 P30 RV hasnt yielded much. Any leads on where to find them at Rick?

BrianB · August 26, 2016, 10:45 AM

Quote from: crd on August 21, 2016, 12:49 PM
BrainB I see you made it back to NY. How did the rest of your trip go? Did you resolve your running out gas issue? I am making the same trip next year in our 89 chieftain and have been following your post. Any advice?

I never did resolve it fully. It comes down to the problem of using what was available off-the-shelf from the parts stores. The SP8016 fuel pumps readily available at Autozone etc can't pump enough fuel for the 454.

Now that I am home, I plan to drop the main tank. I am going to eliminate the in-tank pump and the external fuel pressure regulator. Then I am going to install a high-flowing external pump in the same position as the little one I have (right at the fuel selector valve between the two tanks.

I am confident that will solve all my fuel issues once and for all.

Rickf1985 · August 26, 2016, 12:20 PM

Brian, Just go to Summit.com and look for the big block Chevy stuff. It does not have to be for a P30.

BrianB · August 26, 2016, 12:40 PM

Quote from: Rickf1985 on August 26, 2016, 12:20 PM
Brian, Just go to Summit.com and look for the big block Chevy stuff. It does not have to be for a P30.

Oh yeah... I know. That's the plan. JEGS has them also.

Just wasn't possible when we were on the road and in a different place every day.

Rickf1985 · August 26, 2016, 04:39 PM

Sorry Brian, that answer was actually in response to Kansascat.

kansascat · August 27, 2016, 10:46 PM

Quote from: BrianB on August 26, 2016, 10:45 AM

I never did resolve it fully. It comes down to the problem of using what was available off-the-shelf from the parts stores. The SP8016 fuel pumps readily available at Autozone etc can't pump enough fuel for the 454.

Now that I am home, I plan to drop the main tank. I am going to eliminate the in-tank pump and the external fuel pressure regulator. Then I am going to install a high-flowing external pump in the same position as the little one I have (right at the fuel selector valve between the two tanks.

I am confident that will solve all my fuel issues once and for all.

Brian, i hope for your sake it does solve your problems, but you issues sound so close to what ive been fighting with mine for most of a year and three long road trips, with no success yet that i have my doubts it will. I now have 3 pumps pumping fuel no matter which tank im running on. A elec right next to the tank, a big high flow HD pump just after the selector valve, and the second new mechanical pump on the engine, and its still doing like yours is. Im down to just one in line filter between the big elec pump and the mechanical one. Ive tried eliminating the mechanical pump, then the big elec pump, no change. Ive bypassed the selector valve with no luck. rerouted the fuel line away from engine heat with no luck. Im down to replacing the exhaust system to move it away from the side the fuel lines run down, and replacing the intake to get away from the exhaust heat ports that run under the carb. Been the most frustrating problem ive encountered in many years of mechanics.

BrianB · August 28, 2016, 08:57 AM

Kansascat - I had the "opportunity" to measure the fuel flow rate on the aftermarket "off-the-shelf" electric pump that I had to put on it. Only 1 gallon every 5 minutes. That's just 12 gallons per hour. Not anywhere near enough to feed the carb when the rig is only getting 7 mpg.

I am fairly confident that a better pump will solve my issue.

Froggy1936 · August 28, 2016, 01:24 PM

Your next move is to check the amt of fuel being delivered at the carb . If it is sufficient the problem is in the carb, Plugged fuel filter(inside carb ) Floats set way to low , Metering system inop ! Frank

kansascat · August 29, 2016, 01:35 AM

Quote from: BrianB on August 28, 2016, 08:57 AM
Kansascat - I had the "opportunity" to measure the fuel flow rate on the aftermarket "off-the-shelf" electric pump that I had to put on it. Only 1 gallon every 5 minutes. That's just 12 gallons per hour. Not anywhere near enough to feed the carb when the rig is only getting 7 mpg.

I am fairly confident that a better pump will solve my issue.

According to my math, it actually ismore than enough fuel delivery. At 7 mpg, even if you were running 70 mph that would still only require 10 gallons per hour. Slower speeds would be fewer miles in a hour and even less fuel per hour. Just saying.