Diesel RV Club, an FMCA Chapter

Ask Dave => Hey Dave, I've Got a Problem => Topic started by: Lnorcobra@gmail.com on July 06, 2020, 01:30:27 PM

Title: Extreme low power Cat C7
Post by: Lnorcobra@gmail.com on July 06, 2020, 01:30:27 PM
6/29 Well the first long trip out and bam.... loss of motor power in the
Kentucky mountains. Acts like no power or boost. Yuck. Seems to have a bit of a stumble on throttle between say 900 and 1500. Way down on power, top speed of about 35 warmed up.

*** 7/6 Update ****
Both fuel filters and air filter replaced.
Oil level is correct, oil has about 2k miles on it and appears to be free of expensive sparkles
A little black exhaust smoke
Built an IC tester - one leak found and fixed, small improvement. Previously was only holding ~5lbs, now hits ~13 free revving
Runs MUCH better when engine still on fuel enrichment but barely
Still no fault codes show on either the on board unit, the silverleaf box or the CAT tool
Pac valve appears to be open (cylinder fully retracted resting on stop)
Turbo spins freely with no visible damage on cold side and no shaft play

Injector balance test shows first 3 cylinders fair (31-33) fourth cylinder is high (42) and cyl 5 & 6 low (20-24).  Pump held 3400 no problem.
Tech suggested replacing injectors.

So replace 6 or just the 2 low ones and I guess adjust valves too (30k service was done but coming up on 100k)? Or is there another option before I bite the bullet for the big $$$s? Seems odd to have several injectors fail simultaneously but not familiar with diesels.
Title: Re: Extreme low power Cat C7
Post by: David.e.atherton on July 07, 2020, 02:56:45 PM
Lnorcobra, I can assist you with your problem my phone number is 605 999 0720. What I will
Need is your engine serial number and update on your problem. What it sounds like someone
Diagnosis leading you to injector failure with 2 injectors. Also milage on motorhome. Has
anyone started work on unit. From what appears it is very unlikely that you have injector problems. Give me a brief on troubleshooting problem and any event codes that may be present.
Ask Dave, Dave Atherton Retired Cat Mechanic
Title: Re: Extreme low power Cat C7
Post by: Lnorcobra@gmail.com on July 08, 2020, 05:09:32 PM
Update 7/8

Per Dave's advice I pulled the valve cover to inspect the electrical connectors for the injectors. As Dave suspected, I found some amount of oil in every connector, as well as damage to the insulation on one of the wires going to one of the "bad" injectors, and every single connector was missing the seals.

I ordered a new injection harness and will replace that when it arrives tomorrow. Updates to follow.
Title: Re: Extreme low power Cat C7
Post by: Lnorcobra@gmail.com on July 12, 2020, 04:22:23 PM
Update 7/12
Replaced harness and cleaned injectors connectors. Drove it about 30 miles. Little to no change. Just no power and top speed about 35 mph.
Checking fuel return valve now.
Title: Re: Extreme low power Cat C7
Post by: Lnorcobra@gmail.com on July 17, 2020, 04:04:52 PM
7/17 Update

Removed, thoroughly cleaned and replaced fuel pressure regulator per Dave's advice. No change. Checked fuel pressure and found that it barely made 25lbs at idle and dropped with RPM. Per Dave's advice we're looking into replacing the lift pump with a more suitable unit.
Title: Re: Extreme low power Cat C7
Post by: ziggyh on July 19, 2020, 06:11:07 PM
Did the new injector harness come with seals on the injector connector ends?

Have you tried supplying the transfer pump with a line to a container of fuel.
Title: Re: Extreme low power Cat C7
Post by: David.e.atherton on July 20, 2020, 09:35:17 AM
Ziggyh, yes what you suggested have all ready been approached for troubleshooting the low
power problem. At present the fuel pressure will not meet caterpillar pressure or flow at rated
engine rpms at start up idle and high rpm of which bought the problem back to a failing fuel
transfer pump. Now that problem has been located the owner has ordered the correct parts
to resolve the low power issue. Ask Dave, Dave Atherton Retired Cat Mechanic