Bosch 984 fuel pump

[tomoad]

First off I will let you know I have a 200 promax(Mike Arnolds old boat) but it has been sent to JSRE for rebuilding or upgrading it like Russ Benton's. I am installing a bosch 984 fp or trying to but ran into some hick ups. first i need to know how to wire the pump up. I want the pump to come on when the key switch is turned on, will i have to run a wire from the key switch all the way back to the Fuel pump?? I don't know of anything else to tie into back at the motor, Tonight i was trying to mount the pump in the boat & was in the process of putting the fuel hose on the bottom suction side of pump but was unable to get the -6 fuel injection hose over the barb fitting that is made into the pump. the hose i got was from summit racing, summit brand hose in a -6 which is suppose to be 3/8, my filters i have will accept this hose along with all the other barb fittings 3/8 from the fuel cell, also to the 3/8 barb fitting i have installed in the tank for the return line. If i get bigger hose, then it will fit pump suction side but there goes all of my 3/8 barbs in which it will leak I'm afraid, soooooo should i just try to find some 3/8 fuel injection hose and try and leave the -6 size hose alone??? where can i get this hose, places around the house doesn't have this so i will have to ordered it off the internet. who has a bosch 984 Fuel pump and what size hose did you use on the bottom suction side of pump. this summit -6 size is tuff it will not give any, ID on the hose is .375 and the barb fitting on the end of pump is .475, the summit stuff will not stretch at all, I tried to make it but all i got was bloody knuckles and pissed off. thought I would stop working on it before i slung it somewhere. and collect my thoughts a see if any of you have run into this problem. I do know i will have to have some more hose but what?? My patiece isn't all that good any more. I know goodyear makes a hose also Gates make some, do they flex any??

 

[mtolley]

i get mine from a hydraulic shop. 1/2" from tank to pump, then 3/8" from pump to motor. it will be monday before im back at the shop to get the name off the hose, but its blue, and gas dont eat it up! been on the boat for years without a hickup. i use a 1/4" return line from regulater back to the tank. a stock 39lb regulater has a 1/4" fitting on it and i see no reason to run a bigger hose than that. mt

 

[2fast4mom]

all i got was bloody knuckles and pissed off.

WELCOME to the CLUB!! I have been there and feel your pain and exasperation.

The inlet side of that pump is a freaking METRIC hose size. 1/2" is too big; in my opinion it will suck air even if clamped like the Incredible Hulk tightened the clamp.

I found that 3/8" injection-rated fuel line by Gates would stretch over the fitting if you put some 2-cycle oil on the fitting and the inside of the hose, first rocking it over the $%^& fitting and letting it stretch for a few hours in a room temperature environment.

Have an assistant who is strong hold the pump and rock the hose over the fitting. Mine went on that way, finally, with lubricant...but you have to be careful not to get the lube on your hands, or the outside of the hose, or all is lost.

I know this sounds stupid, but the alternative is to get some European hose and then you're faced with how to attach the other end to the tank fitting!

Believe me, I have been where you are at. Sweating, pi$$ed, wondering how everyone else in the @##$% world has done this.

Somewhere on the board there is a thread I posted on this, I'll go try and find it, it has pictures.

Here it is, 9 or more pages of this BS: http://forum.allisonowners.com/showthread.php?t=1804&highlight=sizzling+fuel+pump

Lou

 

[tomoad]

I got some 3/8 goodyear fuel injection hose(Autozone actually had some) & I can get it on but the inside lining blue part just wads up, I will try lubing it up. Man this is freaking bullsh@t. I got it on but didn't like the way the inside of the tube crinkled up (restriction) some I will try it again. the hose wasn't but $4.29 A FOOOOOOT. I am in the wrong business. Thanks for your help.

 

[GFinch]

:beating dead horse Listen to mtolley about the 1/2" hose. On the intake side there isn't much pressure to clamp off. EFI pumps don't suck well and restricting the inlet with small inside diameter hose will slow the flow to the pump. A long length of hose on the inlet will also slow the flow. Remember it is almost only atmospheric pressure supplying the fuel to the pump.
At $90.00 a piston you could buy 20'+ of hose.:idiot

JohnR, Self Banning 2007, RIP

 

[Rickster]

Remember , you do NOT need EFI hose on the suction side. Regular low pressure fuel line is a lot easier to get on that goofy metric size than the spiral wound EFI hose.

as far as the wiring. I run a 30A Bosh relay and energize it off the back of the voltmeter under the dash.What ever you tie it from be sure it is hot both key on and also starting. I ran this wire to the bilge area and mounted the relay and all by the battery.


Rick

 

[tomoad]

too dam late know I ordered some -8 hose, and -8 barb hose fittings. Now what about the wiring

 

[Myron]

there is a purple wire where your switch boxes are, that is ignition or keyed power, run from there to a relay then to pump

 

[2fast4mom]

You need to use a relay for sure because the pump draws lots of current. I have mine on the Grandsport mounted to the hydraulic trim pump bracket just because it was easy and secure.

Run the purple wire as Myron said to power the electromagnet in the relay (the coil). For the relay switch contacts, attach one side to the fuel pump + terminal and the other side of the relay to a hot 12V primary lead--which also can be found on your trim pump.

In this way, the pump will get all the juice she needs.

BTW these guys are correct about the low pressure side not needing injection hose; I didn't know any better at the time. But I disagree about using 1/2" hose. :idiot It slips over the barb (as you've likely seen) with lots of clearance and I didn't like how clamping it bunched it up. As far as fuel volume goes, in my opinion the 3/8" is plenty big enough.

 

[tomoad]

that's the info I needed, thanks. the fuel hose i ordered is also from summit, the ID of the hose is 7/16. if i don't like it the way it seals i will go with the 3/8, when i ordered the fuel pump from Tony Brucato I also got a fuel relay switch that he sells, its got 4 prones on it, It has a little schematic printed on it but I don't understand it, I also ordered a fuel relay kit from summit (sum-890023) maybe it will have a better diagram in it that i can understand better. I knowed there had to be somewhere back a the motor I could get a signal from but i could'nt check because my motor is at JSRE. Thank you all for your help.

 

[brotherxb03]

I have been running a holley red pump on my carb 2.5 200 for years with no relay,just fused from a picktail wire on the interal harness that is built into the harness from the factory.The wire is at the switch box area a pink,fusha looking color with a black female round stake-0n. Don't know if it's the same on a promax though.

 

[mtolley]

the hose i buy at the hydraulic shop is the same "pushlock" hose that all 4 of the 280's ive got came with from mercury. its 1/2" and it dont bunch up on the inside. i use a little 2-stroke oil and it goes on fairly easily. imo, you need to mount the pump as close to the tank as possible and as low as possible, all of mine are mounted where the fuel pump inlet is at the same height as the bottom of the tank, whether there mounted vertical or horizontal doesnt seem to matter. imo, 3/8" from the pump to the motor is more than adequte(spelling?). i dont like fuel water separaters too much in high performance stuff, dont see the need as i burn all the fuel up in a day anyway and only buy high quality, high test pump gas.( no no- name brand stores that are a nickel or so less per gallon). the return fitting on the fuel rail is only a 1/4" so using hose any larger is asking for a leak! try squeezing 3/8" down to a 1/4" fitting. it doesnt work to good and looks like crap to boot! some say if run the fuel/water seperaor not to plumb the return to it, as it causes air bubbles in the incoming fuel. used to do it that way cause merc said to, but have been doing everything now with the return straight to the tank. just put the return line as far away from the pickup as possible to avoid the dreaded aereated fuel in the line?!
i was told by a well known mercury engine builder that it aint neccesarry to buy the high dollar fuel filters from kinsler and others. i dont have the part number in front of me but seems like it was for an 80's caddillac. 3/8" in and out same micron filter as the kinsler, and cost less than 9 bucks! been running them on 10k plus rpm drag motors and havent had a problem.

i guess ill stop now. if i can help ya any let me know! mt

 

[tomoad]

Thanks MT, I got my hose yesterday and pump is now in the boat, now i am just waiting on the motor, Jay called tuesday & has put my motor together, just waiting on a few odds & in's from vendors. want be too much longer. I appreciate all of the help. wiring up this pump shouldn't be a problem I got a diagram and it looks simple. Now I have a another question, Fuel psi, how do you all monitor it. gauge on the console? or just hook up a little fuel psi gauge (t fitting) on the main fuel hose coming into the motor before the fuel rail on the motor? I also haven't made my mind up on whether or not to go with a pyrometer, I'm sure Tony's PCU will be close, but just want to adjust it correctly & not run it to lean. I've got alot of $$$ in this build.

 

[mtolley]

i only got one boat with a fuel pressure gauge on it. its a mechanical gauge ,so either theres an isolater(i hope) or is direct(with fuel running to the gauge) ive never looked as it has always worked fine. we(my boating group) also has some with electric gauges that use a sender at the motor. seems to work fine
not much on pyrometers, guess i like doing it the old fashioned way of reading plugs and piston tops. the few people i know that use them, they seem to be up and down and not consistenet on a regular basis, and just seem to quit all of a sudden the old method seems to be a failsafe imo.

 

[hack02]

A digital pyro would be the way to go if you opt for one. It'll drive you crazy trying to consentrate on driving the boat and checking rpm and trying to watch those little needles on a pyro guage.

 

[fishnfireman]

Next time your having trouble with a hose that's a little to tight.
Get your heat gun or the old ladys blow dryer..heat it a little then take a pair of needle nose pliers, punch or anything that you can find to bell the end just a little..heat it a again and it will slip right on!!!!