Minivan fuel issues (tank baffles/ jet pump/reservoir /94 style pump hanger walbro 25
So, we've been kicking around some discussions lately and wanted to try and keep my discussions organized and seperated a bit from my main build thread.
Quick summary: Meanmini has a replacement fuel tank that apparently has no sump baffles. She has a Walbro 255 lph HP and has no fuel issues normally. However...
At Cecil running just under 1/4 tank and launching harder than she ever has (due to slowly stepping things up) she found her limiting factor - fuel slosh and pump starvation.
Randy (GLHS60) has suggested running the newer style pump housing or the newer jet pump technology. I just scored this 1994 pump module from ebay: http://pages.ebay.com/link/?nav=item...192801&alt=web
I really just need the reservoir and hanger as i'll have to try to fit my walbro inside.
These newer modules have the sender built in, but in 89 they used a seperate sender. It appears the resistances are the same. I could use everything on the new module and use the wiring harness to make the conversion.
The 1994 fuel tank has one opening, but has no baffles either. If i used it to get rid of the seperate sender hole, then i would end up again with no sump baffles.
My thought was to also change fuel tanks to the Dorman 576013 which has a baffled sump.
I want to fix this once, since i have to go back into this unexpectedly. If with this newer style pump hanger with a built in reservoir there is no further benefit to be had by having a baffled sump, then i might be better to either simply install the new retrofit into my existing tank, or get the 94 tank and eliminate the seperate sender. No really sure which to do.
shackwrrr or Vigo had mentioned about using the newer reservoir style hanger and fitting the older pump to it. If you have some further tips or suggestions i would appreciate any input, or from others who may have done similar.
If i had more time and money when Brian had Mini for all his other great work, it would have been nice to have the tank sumped and an external pump. But one can only do so much and i already had this walbro 255 in tank pump ready for the buildup.
I did watch a cool Airtex fuel pump installation video, which said the vans had a fuel tank drain line. I had noticed a stub fuel line with a cap but never knew what it was for. I figured it was some emission stuff that was plugged.
https://youtu.be/t5JX_AATbtM
Re: Minivan fuel issues (tank baffles/ jet pump/reservoir /94 style pump hanger walbr
The capped fuel line is indeed a drain line. You can start a siphon from it. If you have shop air, an easy way to start that flow is to wrap a rag around the tip of a blow gun and slowly force some air into the filler neck. Obviously you can blow things up if you put 90+psi in the filler neck but if you just apply a little pressure and the drain hose is attached to that plugged line, it should start a siphon flow.
You can also disconnect the fuel hose between the fuel rail and strut tower and put a piece of hose into your gas can or whatever and used the fuel pump to pump the fuel out by jumping power to the coil positive terminal which will run the fuel pump through the ASD circuit.
Re: Minivan fuel issues (tank baffles/ jet pump/reservoir /94 style pump hanger walbr
I thought it was neat. I didn't know it was a drain, and i had planned on using my return line to pump my fuel into a container with the engine running.
Re: Minivan fuel issues (tank baffles/ jet pump/reservoir /94 style pump hanger walbr
Re: Minivan fuel issues (tank baffles/ jet pump/reservoir /94 style pump hanger walbr
Both the Cargo van and several other turbo vans that I have raced did the exact same thing. I get being as light as possible when trying to get a new PB, but just race it with a half of tank of fuel and forget it...
Re: Minivan fuel issues (tank baffles/ jet pump/reservoir /94 style pump hanger walbr
I was good at over 1/2 tank, and i've been good at a bit under 1/2 tank. At Cecil i was right around or just above 1/4 tank and i was ok the first pass but after not so.
Looking back, i might have had a couple times close to 1/4 tank where i could have had this happen and think it was something else.
I can race with 1/2 or a full tank just fine, but i might need every little bit of weight savings to break your van's record and try to break Joe's record! ;)
What i don't want is to have things just right at the track and then have to add more fuel, if that will throw my pump gas to race gas ratio. When things are going good, i don't want to make that kind of change.
But i get what you are saying. I want a simple and cost effective solution.
Having to race with 1/2 tank means i'm rolling with about 70 pounds of fuel weight.
5 Attachment(s)
Re: Minivan fuel issues (tank baffles/ jet pump/reservoir /94 style pump hanger walbr
So my ebay spectra premium SP117 pump module came in today. This was the pump for a 1994 caravan. Attachment 59866
So firstly, what is the line that is just hanging there, the black tubing? It is actually the biggest diameter tube. The small one is the return, and the other large one is the pump discharge. Is this black tube something for emissions/purge can?
Looking it over and seperated the housing. Wow, its got some guts.
Tried to remove the pump, but it would not just pull out, so rather than break something, figured to ask.
Attachment 59867
The other thing i'm thinking with this style pump, with the amount of bypass flow for this jet arrangement, do i need more than a 255lph in this housing to make this work and supply my fuel needs?
Here are some other pics:
Attachment 59868
Attachment 59869Attachment 59870
Re: Minivan fuel issues (tank baffles/ jet pump/reservoir /94 style pump hanger walbr
The black hose is the siphon tube for draining the fuel manually if necessary.
Not sure I understand your jet question ?
Thanks
Randy
Re: Minivan fuel issues (tank baffles/ jet pump/reservoir /94 style pump hanger walbr
Well for one, i can't get the actual pump out. That plastic tube on the pump discharge that goes down for the jet looks like the same oring slip on like whats in the other hanger section, but it doesn't slide apart.
I'm wondering if it is fused together and cant be seperated?
The jet question is, with this setup it uses alot of flow in a recirc for the jet action, correct? Will i need a larger pump than my 255lph in order to still supply enough fuel for 500hp at the rail?
This stock replacement is rated for 50 gph, (~190 lph).
Re: Minivan fuel issues (tank baffles/ jet pump/reservoir /94 style pump hanger walbr
I feel for where your at with the Van right now you need to either run more fuel at the track,
get another tank and have a sump welded to it,or run a fuel cell.
Re: Minivan fuel issues (tank baffles/ jet pump/reservoir /94 style pump hanger walbr
Hi Wayne:
I don't have any experience with the unit pictured, it may be "fused" together.
The two I worked on were an approx. 1994 Dodge Spirit and a 1997 Caravan, both factory assemblies.
They weren't fused together but were tough to take apart as they are sold as assemblies.
I think Vigo mentioned he took a 1994 unit apart?? I'm guessing it was a factory assembly??
I believe he installed another pump, as I did.
The purpose of the canister, or housing, or bucket, in this instance, is so you don't need baffles in the tank.
Even under hard acceleration the pump is in its own little "surge tank".
Fuel pums push better than they suck and sloshing uncovers the pickup.
The jet sucks like a vacuum cleaner, using the venturi effect, to keep the canister full.
The jet doesn't reduce the pumps ability, it enhances it.
Vigo is a shop teacher, hopefully he sees this and explains it better!!!
Thanks
Randy
Re: Minivan fuel issues (tank baffles/ jet pump/reservoir /94 style pump hanger walbr
I follow you Randy and i appreciate the explanations. They are easier to understand with the part right in front of me so i can see how it works.
What i mean is there is always some flow returning around through the tubing within the module for the jet. If the pump flows 50lph recircing around for the jet, that means that flow doesn't get to the fuel rail to return from the FPR. Which means i have reduced some of my available flow at the rail because it is recircing around withing the pump module, does it not? My pump only flows 255lph, and some of that then would just stay flowing around within the tank for the jet effect.
Now if i simply sumped the tank, and used my existing pump and hanger without the jet type pump module, all 255lph is flowing to my rail.
I hope Vigo does see this, so he can respond to how to remove the pump from the can. Maybe Spectra Premium fuses the plastic, and maybe another brand does not.
I have the stock type baffled sump tank on the way, so when it gets here, I'll see how the baffle is shaped. Worst case i just make that work, or add to the baffles.
I wonder if i'm better off to just sump my tank and do an external pump? If i wasn't concerned about the cost right now that's probably what I'd do.
-Tank welding
-External pump
-Pump Suction filter
-Tank Isolation valve
-Fittings
It would all add up to a bit.
Re: Minivan fuel issues (tank baffles/ jet pump/reservoir /94 style pump hanger walbr
Where does the return dump to? Maybe do some mods to use the return flow to run the jet pump instead of the fuel pressure feed.
1 Attachment(s)
Re: Minivan fuel issues (tank baffles/ jet pump/reservoir /94 style pump hanger walbr
Quote:
Originally Posted by
shackwrrr
Where does the return dump to? Maybe do some mods to use the return flow to run the jet pump instead of the fuel pressure feed.
Before it arrived, i thought this was how it may be set up.
The return just dumps back into the canister/reservoir. It is the little stub piece in the top part of the canister, and it looks like there may be a check valve in that plastic stub.
Attachment 59875
The return line doesn't have the same pressure as the pump discharge, so i wonder if the jet would still operate properly?
Re: Minivan fuel issues (tank baffles/ jet pump/reservoir /94 style pump hanger walbr
The jet pump is based on flow not pressure so it would work just fine.
Here is an aftermarket one
http://www.radiumauto.com/Venturi-Je...-Kit-P760.aspx
Re: Minivan fuel issues (tank baffles/ jet pump/reservoir /94 style pump hanger walbr
Good point!!
But I was just reading a fuel pump jet patent and it said not to use the return as the jet looses effectiveness under high demand this way.
""As to using the returning fuel to power a jet pump, this approach has been found to be unsuccessful under conditions of high fuel consumption by the engine. Specifically, when the engine is using more fuel, less fuel is returned to the jet pump and thus less fuel is pulled into the reservoir by the jet pump.""
Fuel diverted was mentioned:
The jet pump assembly diverts a small portion of the fuel exiting the electric pump and aspirates a larger quantity of fuel from a fuel chamber defined by the fuel tank and into the reservoir.
Interesting conversation!!
Thanks
Randy
Quote:
Originally Posted by
shackwrrr
Where does the return dump to? Maybe do some mods to use the return flow to run the jet pump instead of the fuel pressure feed.
Re: Minivan fuel issues (tank baffles/ jet pump/reservoir /94 style pump hanger walbr
Sorry for the late response. The one i took apart was a factory unit for a 1994 3.8 T&C and i don't remember the guts looking exactly like that, although from the outside it looked the same. I can't tell from the pics posted what the best approach would be to getting that pump out. Sorry. :(
Re: Minivan fuel issues (tank baffles/ jet pump/reservoir /94 style pump hanger walbr
Well, i've tried a few times to seperate this fuel pump, but i can't break it down any further than the pics earlier.
I'm thinking of just breaking this apart and using the reservoir around the pump and the baffled sump fuel tank to see if that works.
Or i just will change tanks and hope that works.
Re: Minivan fuel issues (tank baffles/ jet pump/reservoir /94 style pump hanger walbr
Too bad you couldn't find a used OEM takeapertable unit and return the Spectra.
Sorry if I led you on a tough road.
More G.M. guys seem to like the jet than others.
Best of 2017 Wayne!!
Thanks
Randy
Re: Minivan fuel issues (tank baffles/ jet pump/reservoir /94 style pump hanger walbr
Quote:
Originally Posted by
GLHS60
Too bad you couldn't find a used OEM takeapertable unit and return the Spectra.
Sorry if I led you on a tough road.
More G.M. guys seem to like the jet than others.
Best of 2017 Wayne!!
Thanks
Randy
I'm considering ordering this one, to see if the pump can be removed and replaced with my walbro. But wish i knew it would work, so i don't end up with another paperweight!
http://pages.ebay.com/link/?nav=item...539907&alt=web