New Holland Guardian SP310 Slow Crank/Hard Start

muttnjeff · Post by **muttnjeff** » Tue Apr 20, 2021 6:30 pm

: Sprayer 310

Spent some time with a field tech looking over a sprayer, FPT engine - 6 cyl - 6.7L - Common Rail

Machine was at roughly 80hr when the issue began occurring, main complaint slow/hard starting.

Tech had went the way of a fuel system problem, replaced the HP pump as it also contains the lift pump and replaced the main filter housing as it contains a check valve to prevent fuel drain back to the tank.

The first thing we checked was the fuel supply, scoped the metering valve PWM, rail PSI sensor output and CMP/CKP correlation, did a 3 start/stop test, all checked out good.

New Holland_SP310_2021_Diesel_20210415-0003.psdata: Start & Stop Test 1; (4.97 MiB) Downloaded 360 times

Next we traded the the fuel leads for the amp clamp to do a relative compression test.

New Holland_SP310_2021_Diesel_20210415-0004.psdata: Rel. Comp. Test 2; (1.88 MiB) Downloaded 368 times

Next was to check a known good machine for CMP/CKP correlation and compare the relative comp waveform.

New Holland_SP310_2019_Diesel_20210415-0007.psdata: Known Good Test 3; (1.39 MiB) Downloaded 332 times

Once we had the data collected we sat down and went over the results.

SP310 MY2021 Slow Start.pptx: Test 2 & 3 Comparison; (328.18 KiB) Downloaded 360 times

Our findings were the fuel system is spot on as is the CMP/CKP correlation, the starter current was odd on the problem machine and after getting the known good for comparison I knew we were onto the source of the problem.

After having a chat with the tech & service manager we determined the likely source of the higher than normal load on the engine was the unloader valve (malfunctioning) for the main hyd pump.

The valve coil is commanded on (unloading) during startup, once the ignition is released to the run position, the coil de-energizes putting the pump into a full load state.

The tech tested the coil for short and open, all was good, ran a independent 12volt feed to the coil and the engine cranked and started in <4 sec. where before it was upward of 10 sec.

There was no concern for the ground side of the coil wiring as its a shared ground and the machine had no other issues. The hyd control is a Parker iQAN system, it was determined that somewhere in harness from the iQAN node to the coil it suffered a broken wire.

Post by **ben.martins** » Tue Apr 20, 2021 10:31 pm

Thanks muttnjeff for sharing this and it makes a great read! Wondering if this could be something we can share in our newsletter?

Interesting fault with this machine and it's amazing how a broken wire can send you down so many rabbit holes!

Thanks again and keep up the good work.

Kind regards

Ben

muttnjeff · Post by **muttnjeff** » Tue Apr 20, 2021 11:09 pm

Thank you Ben, by all means if Pico would like to use the experience fee free to do so.

Post by **ben.martins** » Wed Apr 21, 2021 8:58 am

Thank you, I'll run it past you before anything goes out.

Just looking at the fix capture and I wonder if the starter motor might be the next item on the list!

Thanks again and catch up soon.

muttnjeff · Post by **muttnjeff** » Thu Apr 22, 2021 4:20 pm

No doubt the starter, batteries and cable were all tested throughly!!

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