[PROJECT 'REVERSE JURY-RIG' (PRJR)] Fuel Delivery Diagram Needed

[ArchLAB]

Subject: 1971 Blazer 4wd, 400ci w/ 3spd Manual
I am just starting on my Blazer Project which, by the Project's name, should give you an idea of what I'm tackling. This Blazer's body is in really good shape, but one of the previous owners was one of those guys that can't just go from 'A -to- B' with MECH & ELEC....I mean, things generally work, but this truck is 'Bumpkin Engineered'.

So, what I'm attempting is this: I want to get this Blazer into a more orderly & logical condition. One of my first steps is to cleanup the Fuel Delivery System - from Tank to Carb. The Tank seems to be off of a 1980s or 90s truck because it is a Plastic (ABS?) tank. There is also an Electric Fuel Pump connected directly to the Fuel Tank, so I doubt that's 'standard', but it might be a necessary addition. WHo knows?

Those changes might actually be good, I suppose, but I would like to know what is 'natural' for a 1969-72 Blazer & what is not.

I'm not necessarily trying to go back to 'All Original' because I believe in updating & improving my vehicles to at least 1980 standards (LOL). As such, can anyone post, or direct me to a Diagram of the Fuel System for this era of Blazer. I promise to buy a manual, but I just need to accomplish Phase 1 & get this beast running. BTW, recommendations for which Manual to get will be appreciated.

Thanks to you knowledegable Blazer-ians.

 

[dremu]

Ah yes, the un-messing what's been done by the last guy. I have sometimes wanted a previous-owner-seeking missile. (Sadly, sometimes I want a missile to seek out my own idiocy too )

The be-all-end-all of service manuals is of course the factory service manual. Best bet cost-wise is Ebay, or you can get them new (spendy) from Helm @ http://www.helminc.com/ The Chilton's or Hayne's aren't bad and cover general repair procedures in addition to the specific stuff in the factory book.

Your truck would have had a mechanical fuel pump factory. Some folks prefer electric for steadier pressure, but depending on type it might need a regulator (the mechanical one includes it, IIRC.) The electric pump also "pushes" more, as it's closer to the tank, vs the mech "pulls" as it's up front. I remember with my carb setup that priming the pump took a while if it hadn't been run for a while, as fuel would drain back out of the pump.

The plastic tank is aftermarket, but is likely designed for your truck, as I don't think tanks for the later ones are the same size as yours. The sending unit is the important bit here as it has the hookups.

You might look under the hood for an emissions diagram, which would include vent lines. If you can locate a vacuum diagram this will be related.

My memory of my '74, which should be similar to yours, is that there's a 3/8" supply line from the tank, travelling down the passenger frame rail, to the fuel pump, and then to the carb.

There's a 5/16" vent line from the tank, also down the frame rail, to the evap/charcoal canister up front. This then has a vacuum line to the carb.

That should get you started anyway.

-- A

 

[ArchLAB]

Thanks Dremu.
That does indeed get me started. Anyway, today I pressure washed the underside, removed the tank & cleaned out the old gas (I always hate how that
stuff smells...& how to dispose of it as well).

An Aftermarket tank might just be what I've got, as it seemed to fit in perfectly. Anyway, the Plastic tanks sure clean out easier than metal.

Sending Unit: I'm also gonna test this as well.

As for the pump: I'll test it tomorrow. If it works, I may keep both pumps on. MIght be overkill, I guess I'll see.

Regarding the Lines: I'll also see if they're still flowing correctly. Hope so. I'm replacing the rubber lines w/ Alcohol-spec rubber. I did a conversion to E85 on a '67 Barracuda a few yrs back & that rubber was key. I also had an Alcohol-spec Elec Pump which worked well. Maybe I'll dig that out again if the Elec pump already installed is shot.

As for the Manuals: I'll be combing EBAY. If I could find a Factory Manual for my old '69 Dodge Truck, I'm sure that a Chevy Manual will be easier to find.

....continue Phase 1....