Fuel Injection Trouble: Diagnosis Requested

Fuel injector problems with an S-10 Blazer . . .
Can't get cold start without starter fluid, or by first switching on the ignition to run the fuel pump 3 or 4 times in succession before
cranking.
I brought it in for a fuel pump pressure test. It registered slightly below specs, and this is apparent from the way it wants to stumble or fail at start up with the ignition priming procedure or any hot start. So, it will, at times, start hot, but weakly.
Trouble is, you hear differing opinions, some guys saying that a fuel pump either works or it doesn't. Since the car runs without stumbling or quitting once it gets started, this might seem to support their view, except that you consider how vacuum is induced to the fuel line once the engine is up and running, which might well explain why it runs fine once it gets started, and why it's hard starting without the aid of that suction from the manifold.
The problem got started not long after I stupidly put some cheap, bargain priced fuel treatment in the tank. It had the odor of that old fashioned carb cleaner. I thought maybe it might have dislodged some gunk from the tank, to clog up the fuel filter, so I replaced that. No change.
Going on the assumption that the mechanic who ran the test was right on the money (my money, the 500 bucks he was talking) about the fuel pump needing to be replaced, then that's the job I'm going to be doing myself, to keep that money, so much as I can, in my pocket instead of his. So here's the thing . . .
I talked to a guy the other day who told me he had the same problem with his car, and fixed it by an easy workaround: he bought an external electric fuel pump; didn't have to drop the tank. It must have been somebody else who did the work for him, because he couldn't tell me what was done with the wiring.
Obviously, they just left the bad in-tank pump where it was, since there was no dropping of the tank required. Pressure from the external pump would simply suck the fuel right through the in-tank pump, turning the impeller just like wind through the window driving the blades of a switched off fan--nothing to it. Best I can figure, they must have simply disconnected the wiring harness from the old pump and connected it to the new in-line pump, where it was mounted to the chassis along the fuel line somewhere between the tank and fuel filter.
The guys down at the auto parts store were horrified to hear this, predicting all sorts of disaster for the computer and many another thing. Even so, the man who told me about it swears that it fixed him up, and gave him no such trouble, working just fine from that time on.
So what you all think--or what have you heard, or seen, or done, hand's on?
I do find a "Mr. Gasket" micro-electric fuel pump at O'Reilly's for about 40 bucks, but on their website they stress "NOT for fuel injection". Clearly, you'd need to get a pump that delivered the correct pressure and volume to the injector, which might require a pump of a slightly higher capacity than the in-tank pump, since it would work against more resistance with that extended intake line.
It begins to sound kinda hairy, I guess. -- JP
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

500 bucks sounds like a bargain price for replacing the fuel pump. and BTW, manifold pressure has no effect on fuel pressure in a fuel injected engine. The external pump will be a waste of good money. Regards, JR
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Horse Shit if it is. It'll be $500.00 I never in this life spent if I fix it my DAMN self, pard. So think that over for a God damn minute, neigbor of mine.

Bull Shit. Utterly impossible.

PROVE IT.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I see that my Friday night whisky was talking loud, noisy and stupid as ever. I apologize for this noise. -- JP
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote in message

I see that my Friday night whisky was talking loud, noisy and stupid as ever. I apologize for this noise. -- JP
I appreciate that. Regards, JR
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
JP wrote:

If the pump is below spec, replace it. They only get worse over time. The reduced pressure is due to either the brushes/commutator being worn or the wiring to the pump is starting to so bad. When the pump gets replaced be sure you also replace the connector pigtail (comes in the kit)

Probably did two things, cleaned the brushes in the pump and flushed some crud into the pressure regulator as well.

$500.00 for the parts and labor isn't a bad deal. The pump alone is $300.00 or more if this truck is newer that 1996, a bit over 90 if it is the earlier spider style and about the same if throttle body.

They would have had to chase out the wiring if they wanted a working fuel gauge. It is in the same harness.

The external pump will end up costing you more than you will pay for the in tank unit. PLUS you will need to run new wiring and plumbing for it to operate.
What year is the S-10 and is it a P/U or Blazer style?
If it's a P/U the easy way to change the pump is actually to pull the bed off. Then you can get to the pump and fuel lines without moving/bending them. Plus you don't have to fight with the tank and fuel. About the best price on a good pump is from rockauto.com They have factory pumps for less than half what your local dealer will want. DON'T buy based on price. Unless you like changing umps more often. And DON'T skip changing out the connector. They have a nasty habit of heating up and losing the spring in the connectors themselves. That just starts a cycle that a new connector will stop.
--
Steve W.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
<snip a whole bunch of valuable info>

It's a '93 Blazer.

Thanks. I'll check that out.

You mentioned the possibility of gunk getting into the regulator. Should that be replaced or--if possible--cleaned, first of all, to see if that might improve the situation?
Also, on the recommendation of an auto parts store guy, I bought a can of this "Sea Foam" injector treatment. He suggested running it straight into the system via the vacuum line from the brake booster. What's your view on that?
Thanks again!

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
JP wrote:

OH well so much for the easy way. The 93-95 are not real bad but the way the fuel lines run to the tank is a pain, Plus they are steel lines with just short rubber sections. VERY easy to break them if they are rusted. PIA to replace if they break. One of the reasons I like the 96 up versions is the plastic fuel lines and quick disconnects on the fuel pump module. SO much easier.

No problem. Being a '93 you can replace just the pump and the fuel sock. Should run about 90 bucks for the pump and 5-10 for the sock.

No way to clean it. They are a small sealed unit that attaches to the back side of the injector.
The test procedure is to use the pump to pressurize the system. If the regulator is bad it will can show in a few ways. It will drip fuel out the vacuum fitting on the back. It will drop pressure VERY fast once you turn off the pump. or it will either raise the pressure to the pump limits OR not build pressure over about 10-12 pounds depending on the failure inside.

That is how you can clean out the top end of carbon and crud. It will NOT clean the injectors or anything in the fuel system. The vacuum fitting is downstream of the fuel delivery parts.
However it isn't a bad thing to do if the engine has been burning any oil OR has been running rich for a while.
BUT two warnings about this method. DO NOT DO IT INSIDE A GARAGE. And an even bigger warning. DO NOT under any circumstances do it with the tailpipe aimed at ANYTHING you want to stay clean!!! All the carbon and crud comes out of that pipe like a fire hose full of black paint!!! Along with the carbon comes the SMOKE cloud that you could use to hide a tank battalion...

--
Steve W.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Thanks, Bill. I'll check this out. -- JP
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.