We just got back form a 1500 mile round trip and boy are my arms tired. Actually, it was tiring keeping the van on the road the first half of the trip with the worn steering box. Some kind folks swapped in a good used box so the return trip was a pleasure. So much for that. We were loaded to the gunwales burdening the tired 5.8 off the line and over Mt. Shasta and Hwy 97 through Oregon. Lack of power is one thing and my basis of comparison are similar loads in a '97 Suburban 6.5 TD which hardly feels the load and an '00 Dodge B3500 5.9 which doesn't feel as burdened. I can't speak for the early life of this 5.8 but what concerns me is light sputtering at WOT in OD. The sputtering might occur in 3rd but when I feel the sputtering I manually defeat OD and back off the pedal. I installed a new NAPA premium filter prior to the trip and there are under 5000 miles on new plugs and wires. Is there a way to test fuel pump flow without removing the fuel pump? What might be a related issue is it threw the check engine light a couple of times in local non-WOT driving during the trip. I found a 543 fuel pump code and an EGR code. I'm battling an intermittent AC blower fault which I traced to some melting in the relay and socket. I swap the blower and horn relays and the blower comes to life. I swap back the relays and the blower stays funcitonal. For kicks, I swapped the horn and fuel pump relays. I haven't reset or checked for codes since but the check engine light stayed off over 730 miles though the sputtering remains. Check engine light occurrences don't correlate with sputtering. Thoughts?
I'm not familiar with your engine or its ECM strategies but I'm assuming its a high pressure fuel injection system---correct?
If so there is or should be a test port on the fuel rails under hood---you'd need the proper gauge installed, test drive the van under various throttle conditions, noting the pressures. This would probably be the most accurate test of the existing pump and the entire fuel system up to the injectors.
Sounds like a decent running van otherwise---glad your trip wasn't more "eventful", mechanical wise!
There is a "Schrader" valve on the fuel rail, drivers side, front, accessible from the front of the van, after taking off the air ducts to the TB.
Has a black cap on it, and it "looks like an air valve" fitting.
Get a hold of a fuel pressure tester, and you should read 35-45 pounds pressure with the key on, engine not running, with engine running, you should read around 30-35 pounds pressure, anything below that, bad pump.
But, before you run out and buy a new fuel pump, or sending unit, pull the old one out and check the sock filters in the tanks, a van that old, the in-tank filters could be plugged up.
If you can wait a few days, order a new pump from Rockauto, if not, Napa seams to have the best pump for a quick replacement, and if you can, take the old pump with you to the store, because there are a few different style/models for the E series.
And, get the new sock filters for the new pump while your at it, and a new "O" ring/lock ring for the sending unit/tank seal.
My '88 had those same symptoms minus the CEL. A pressure test while driving in town read normal
Fuel pressure and manifold vacuum gauges
However, when I pulled the in-tank pump out, the filter sock was almost totally clogged with some kind of scaly substance. So, at highway speeds, it was running out of fuel. Since I figured the scaly stuff was probably everywhere, I replaced the pump and sock and that fixed it.
I had an A/C blower problem too. Front blower only, rear blower worked fine. Some days the front blower would work, other days not. Pulled it all apart, found nothing wrong? While driving one day with the front blower dead, I wiggled the ignition key and the blower started working!?! It has been working ever since. No clue as to why.
'88 E150 clubwagon