Is my Electric Fuel Pump not working?

HandyDan · December 21, 2011, 06:31 PM

Well, I went out and decided I would go fill up with gas while the prices were down ($2.89) but the old 454 wouldn't fire. I ran down the battery trying to troubleshoot it but no luck. I even tried starter fluid which got it to fire and run until the starter fluid ran out, but no joy on gasoline. I turned on the key but got out of the coach and went back by the gas tank to listen for the electric fuel pump. It was buzzing but not as loud as it normally does. I think that is the culprit. It may be trying to pump, but I don't think it is getting the job done. I have a mechanical pump on the engine but it can't pull gas through the electric if the electric isn't working. If the weather stay good tomorrow, I'm going to bypass the electric and see if it will run on just the mechanical. It might get me to the gas pump and back (3 miles one way). Do electric fuel pumps make noise but don't pump?

recycled55 · December 21, 2011, 07:01 PM

If I remember correctly those kinds of pumps are designed to be "pushers".
It should be back near the tank and yours appears to be up near the engine.
They are very weak used as a "puller"
I had one fail years ago while I was in a gas station getting gas and there was no mechanical pump back up. After that I had two elects with a toggle switch to select one of them.
I could be wrong it does happen but rarely....
recycled55

ClydesdaleKevin · December 21, 2011, 07:59 PM

Hey Dan,

I'm pretty sure that the electric fuel pump on yours should be in the tank, like mine. That said, someone in the past added the electric fuel pump in your picture, probably because the one in the tank was bad and they didn't want to drop the fuel tank.

The mechanical pump alone should start and run your engine, but at load, either pulling hills or accelerating, its going to bog and sputter...vapor lock. If you take it easy, it should get you to the gas station.

I have had electric fuel pumps go bad, but they still hum and make noise.

Try bypassing the add-on fuel pump and see if she starts. If she does, you know the pump is bad/blocked/whatever. If it still doesn't start, leave the add-on pump bypassed, disconnect the fuel line exiting your mechanical fuel pump and have someone turn your key, while you hopefully catch the gas that spurts out of it into a container. If it doesn't spit gas, your mechanical pump could be bad. The add-on pump might have been bad for a while, and you could have been running off just the mechanical. The alternative could be a blockage at the tank pump...the sock filter at the fuel pickup could be grossly blocked with varnish and rust particles, in which case you'll have to drop the tank anyway, so you might as well replace the in-tank fuel pump...not expensive...and the sock, also cheap...and get rid of the add-on pump, which is unnecessary if the in-tank and mechanical pumps are working.

Before dropping the tank, you can hook up a fuel line to your mechanical pump inlet, drop it down in a container of gas, and again, have someone crank the engine while you catch the gas that hopefully spits out of the outlet. If it doesn't spit out under this controlled condition, you know the mechanical pump is bad...around 30 bucks.

Eventually you'll want to drop your tank anyway and replace that pump, and eliminate the add-on...recycled55 is right...the add-on will never deliver enough fuel for proper performance since it is so far from the tank and has to "pull" the gas. The 454 needs the pusher type pump in the tank, in conjunction with the mechanical pump, to deliver just the right amount of fuel in all conditions to avoid vapor lock.

Kev

Froggy1936 · December 21, 2011, 08:50 PM

Here is my 2 c worth I have never heard of a pump in the tank on a carburated veh (only fuel injection) The mechanical pump cannot pull fuel thru a electric pump in sufficient quantities to run above idle or low speed (see pic for proper routing) I do not use my electric pump except in case of vapor lock (very hot day and A/C on) my mechanical pump will pump a gallon of fuel in 18 sec & the electric will pump a gallon in 12 sec either will do the job i mounted my electric midway mostly due to ease of installation - Frank

DaveVA78Chieftain · December 21, 2011, 09:33 PM

First, go to the Members Free Manuals section and download the Chevy/GM P-30 Service and Maintenace Manual (19Mb). Turn to pdf page 136 (Appendix 7-7 Vapor lock section). That section contains the following electric fuel pump and regulator nformation.
Due to reported vapor lock issues, GM started recommending the installation of an electric fuel pump and regulator in 1984. How to add the pump is clearly described (yes an electric pump needs to be real close to tank). In 1985 1/2, GM started installing an electric fuel pump in the gas tank with a external regulator. At this point they engine was still carburated. GM did not convert motorhomes to TBI injection until 1991.
Lots of info in that free manual which is also repeated in the regular service manuals.

Dave

recycled55 · December 21, 2011, 10:07 PM

Froggy1936 is that vertical brass fitting in your picture a one way check valve to allow bypass?
If that is correct "I like that". Never thought of that idea.
recycled55

Froggy1936 · December 21, 2011, 10:57 PM

Yes its a one way bypass, So when i turn on the electric pump it does not just go around in circles . And the mechanical pump does not have to pull thru shut off elec pump. I have not heard of the elec pump in the tank for vaporlock in fact i never heard of vaporlock being a problem But i was with Volkswagen from 1972 till 1991 so i heard very little of domestic veh problems. P.S. VW had fuel injection in 1968 Type III Pump not in tank

HandyDan · December 21, 2011, 11:30 PM

Okay, recycled55, you caught me. I hoped no one would notice that the pump was in the front wheel well. That was the way it was when I bought the MH two years ago. I had the picture in Photobucket and I didn't have one in its present position. I moved the pump to the frame just in front of the gas tank. It does not have a pump in the tank. When it was first manufactured, it only had a mechanical pump on the engine. I suppose it ran okay at that time. I have the Service Manual on my computer and I moved the fuel pump back per the suggestions in the manual. When I bought the MH it did not have a mechanical pump at all. The electric pump was all it had and it wouldn't run worth a hoot. That's why I replaced the mechanical and moved the electric. However, I REALLY like the way Froggy1936 has his configured. I'm going to look into that. Thanks! Would you happen to know what pump that is?

Froggy1936 · December 22, 2011, 10:37 AM

As per the lable on the bracket its a Holly The one way brass valve in 3/8 female in & out was about $60.00 I had a cheap pump that only lasted a short wile Replaced it with the Holly If you are interested i can look through my bills and find out where i got it Make shure you add a filter before the electric pump as they are very suseptible to particles (jam the rotor) Frank

ClydesdaleKevin · December 22, 2011, 11:06 AM

Oops! I forgot yours was an 84, and they didn't add the in-tank pump until around 86. My bad! And since you already moved yours to the tank, none of my post applies except checking the mechanical pump, and the fact that an electric pump can still make noise, but not move fuel.

Kev

Froggy1936 · December 22, 2011, 11:48 AM

After looking at the manual it looks like 7/1985 the electric fuel pump was added to the tank & i think this also was start of TBI injection and end of Carbuerators Not shure though to hard to read manual with computor But i also noticed a one way check valve that GM used From Aluminum Fabricated Products AFP 200 that looks less expensive than mine. & you cant beat electric pumps Just carry a spare just in case I carry a spare Starter Alternator & fuel pump along with hoses belts cap coil wires fuses bulbs etc Frank

DaveVA78Chieftain · December 22, 2011, 03:02 PM

As I said before, for Motorhome chassis, GM did not start using TBI until 1990 / 1991. Electric Fuel pump was interium Vaporlock fix until they started using the higher capacity (18 psi) in-tank electric pumps needed for TBI. The inline regulator you see in the 85-89 chassis is used to bring the pressure down to the 5 psi level of a carburator float needle requirement. You will also notice that on 90 and later TBI they did not have the in-line regulator because a 220 Model TBI unit has the pressure regulator built into it in order to maintain an TBI injector pressure of 9 - 13 psi.

Dave

HandyDan · December 22, 2011, 08:56 PM

Well, the wind chill was 29 today with a slight breeze and overcast skies. My old bones just didn't feel like laying on the cold ground so I didn't do anything with the fuel pump today. It is supposed to get warmer later this week. Instead I worked on the batteries. I charged up the chassis battery (I had worn it down trying to start the motor) and I replaced the coach battery with a larger one. I don't use it very much but the old one was 6 years old and starting to show it's age. I did a fireworks show for a few seconds because I forgot that I was still plugged in to shorepower. Once the positive cable touched the bottom of the battery compartment, things got real interesting. I need to run all new battery cables. When I bought the MH someone had cut the cables and stolen the batteries out of it. I put new ends on what was left of the wires and made do, but it would be a lot more convenient if the cables were longer. Especially if the positive cable would reach out of the compartment.

HandyDan · December 22, 2011, 09:20 PM

Froggy1936, I have been studying your picture and trying to decide which way the fuel is flowing. Is the front of the chassis to the left or right of the picture? I have been trying to find a check valve similar to yours but so far have come up empty. I found a plastic one that was $92. The whole fuel pump doesn't cost much more than that! NAPA tried to help but couldn't figure out what I was talking about (young kid, not much upstairs if you know what I mean). Searching online I found lots of other types of check valves, just not for fuel. I'll try Reilly's tomorrow or maybe Advanced Auto.

DaveVA78Chieftain · December 22, 2011, 10:18 PM

A few possibilities:
http://www.ebay.com/sch/i.html?_nkw=inline+fuel+check+valve

http://www.jegs.com/webapp/wcs/stores/servlet/KeywordSearchCmd?storeId=10001&catalogId=10002&langId=-1&Ntk=all&Jnar=0&Ne=1%2B2%2B3%2B13%2B1147708&searchTerm=fuel+check+valve

http://www.aeromotion.com/id62.htm
Dave

HandyDan · December 22, 2011, 10:35 PM

Thanks Dave. Gee, the prices sure run the gamut. If all I want it to do is keep the gas from flowing backwards, why wouldn't one of those cheap ones work? I'm concerned about the amount of gas flow. Could that be the difference between a $8.00 and a $80.00 one? I wouldn't go any smaller than 3/8".

DaveVA78Chieftain · December 23, 2011, 11:47 AM

Not sure Dan. I have never messed with a fuel check valve. Only thing I can suggest is beat the internet for reference information.

Dave

Froggy1936 · December 23, 2011, 11:56 AM

The flow is left to right in the Pic The valve i used is from Check All Valve Mfg Co. (515-224-2301) checkall.com $76.95 + $7.32 Freight Pt No M3BBRMT.125SS 3/8 Female The Pump from Holly Performance 6145-2 Red Auto $127.31 The check valve used by GM is from Aluminum Fabricated Products AFP200 it looks less expensive Availability unknown Frank

Froggy1936 · December 23, 2011, 12:04 PM

Looking at Dave,s suggested sites I would use the 1 way flow, filter with ck valve $29.95 in 3/8 Good price + filter And i would not go smaller than 3/8 Frank

ClydesdaleKevin · December 23, 2011, 12:34 PM

When GM fixed the vapor lock problem in 85ish, and put the electric pump in the tank, they also upgraded everything to 1/2 fuel lines, so yeah, don't go smaller than 3/8s.

Kev

jkilbert · December 25, 2011, 07:58 AM

since part of the discussion turned to vapor lock, don't for get that "modern" gasoline is formulated to run best in fuel injected vehicles. it has a lower vapor pressure and will boil quickly, thus leading to vapor lock. in EFI motors, not a problem since gas is constantly returned to the tank. in our beasts it sits in the fuel bowel of the carb where is can boil away. modern in tank pumps are a much higher pressure usually 45-60psi for EFI motors whereas your carb is around 9psi. i switched to an electric pump when i got my winnie. i'm using a pump from Summit Racing mounted right next to my tanks. since this is under the coach i have 1 power lead with no splices in it and my stake-ons are sealed with liquid electrical tape. make sure all grounds are in good condition. especially battery to frame and engine to frame and pump to frame.

ClydesdaleKevin · December 25, 2011, 08:52 AM

With the 1/2 inch fuel lines, electric in tank pump, and the mechanical pump, GM pretty much did eliminate the possibility of vapor lock in the carburated 454...we've never experienced in our 89 HR...used to get it pretty often in the 77 Itasca.

Kev

HandyDan · December 28, 2011, 07:22 PM

Today the temperature finally got up enough that my old bones could work outside on the electric fuel pump. I loosened up the tag axle wheel and then jacked up the rear of the MH. That wasn't a big deal since I have hydraulic leveling jacks. It is just a matter of pulling a lever. Then I removed the wheel so I had easy access to the fuel pump. I removed the pump and had a plug ready to plug up the gas line. However, it wasn't needed because no gas came out. That should have been a clue, but I'm old and absent minded so I kept going. The thought occurred to me that the fuel filter might be clogged so I removed it, also. Then I stuck on a long fuel hose to the pump and put the other end in a gas can. I wanted it long so I could be away from the gas can in case I made a spark when I hooked a battery on to the pump. The pump worked just dandy. Gas was shooting out. So, I blew out the filter with my air compressor and could not see anything wrong with it. While scratching my head trying to figure out why the MH wasn't getting gas it hit me that no gas had come out of the fuel line. I tried blowing into the fuel line and listened for bubbles in the gas tank. Nothing. I was smart enough not to suck on the line. I'm not that old, yet, but I did have a vacuum pump for getting oil out of my boat. I hooked it up and tried pulling some gas out. Nothing. I think I went to a lot a trouble just to find out I was out of gas. Now here is the kicker. The generator still works. I can get it to crank up and run. Which makes me wonder if the fuel lines for the MH and generator are switched. It had to have been before I got the MH because all I did was install the electric fuel pump on the old gas line to the carb. Well, the sun went down before I could get everything buttoned up and further experimentation.
Tomorrow I'll try putting the 15 gallons of gas I have in cans I keep for the lawn tractors, mowers and other small engines in the MH and see if that makes a difference. I should have tried that first.

DaveVA78Chieftain · December 28, 2011, 07:58 PM

Hmm, I just cannot wait to hear the rest of this story

Dave

ClydesdaleKevin · December 29, 2011, 08:57 AM

Could be a switched line...on our old Itasca it was switched, and we found out the same way...the genny would still work, but the engine wouldn't run until I added more gas.

Hopefully it isn't a pickup tube problem, which would require a tank drop and a new sock, if the pickup tube didn't rust and fall off into the tank. It can happen, but I seriously doubt it happened on yours...its only a couple of years older than ours.

And sure...rub it in with the hydrolic leveling jacks...lol!

Kev